Agricultural product coating material, coated agricultural product and preparation method

Abstract

The invention relates to the technical field of agricultural product processing, in particular to an agricultural product coating material, a coated agricultural product and a preparation method. According to the invention, polyhydroxyalkanoate with specific performance is used as a main coating material for coating agricultural products, and in the coating process, a traditional high-temperature film forming process is not adopted, but a film can be formed at the temperature of 40-70 DEG C; therefore, the adverse effects of high temperature on contents (such as seeds, organic fertilizers, agricultural medicines and the like) in the coated agricultural products can be reduced or avoided. The agricultural product coating material provided by the invention is suitable for coating various agricultural products (such as seeds, fertilizers, medicines and the like), and can achieve the purposes of protection and slow release. The coating material provided by the invention is used for coating agricultural products, and the obtained coated agricultural products have higher heat resistance after coating is finished. In addition, the agricultural product coating material provided by the invention is environment-friendly, can be degraded in a soil environment, and does not cause environmental pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural product processing, and in particular to an agricultural product coating material, a coated agricultural product and a preparation method thereof. Background Art

[0002] Agricultural product coating technology mainly refers to the use of coating to protect or slow-release agricultural products such as seeds, fertilizers, and medicines. Currently common coating materials include polyethylene (PE), acrylic acid, etc. PE-type coating materials are usually coated after preparing the solution using an organic solvent method. The use of organic solvents has a greater risk of environmental pollution. The preparation of acrylic coatings is usually carried out in the form of an aqueous emulsion and does not involve organic solvents. However, the coating materials obtained from acrylic acid aqueous emulsions are similar to PE-type coating materials, and both have the problem of non-degradability. After disintegration, PE-type coating materials and acrylic coating materials will remain in the soil, forming microplastics that enter the groundwater, or cause soil compaction and reduced grain production.

[0003] Polyhydroxyalkanoate (PHA) is a general term for biopolymer polyesters, including monomers and copolymers. With the development of synthetic biology, PHA copolymers synthesized by microorganisms are divided into random copolymerization and block copolymerization. More than 100 different monomers have been reported, most of which are 3-hydroxy fatty acids with a chain length of 3-14 carbon atoms. Due to the wide variety of PHA monomers, the physical and chemical properties of different PHAs vary greatly.

[0004] As a biosynthetic polymer thermoplastic material, PHA usually has good biodegradability and biocompatibility and is considered to be an environmentally friendly material. Therefore, researchers have tried to use polyhydroxyalkanoates as agricultural product coating materials. However, existing polyhydroxyalkanoates usually need to be dried at a temperature above 120°C during coating, which may have an adverse effect on the contents of the agricultural product coating.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides an agricultural product coating material, coated agricultural product and preparation method which are environmentally friendly and degradable and have performance that meets the requirements of use. The agricultural product coating material provided by the present invention is suitable for coating various agricultural products (such as seeds, fertilizers, medicines, etc.), and can achieve the purpose of protection and sustained release. The PHA coating material itself can be degraded in the soil environment and will not pollute the environment. At the same time, when the coating material provided by the present invention is used for coating agricultural products, the coating temperature is relatively low (not exceeding 100°C), which can effectively reduce the adverse effects of high temperature on the contents. In addition, when the coating material provided by the present invention is used for coating agricultural products, after the coating is completed, the obtained coated agricultural products have higher heat resistance.

[0007] Specifically, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides an agricultural product coating material, comprising the following components in parts by weight: 20-45 parts of polyhydroxyalkanoate, 0.1-1 part of emulsifier, 0.1-1 part of leveling agent and 0.1-1 part of wetting agent; the polyhydroxyalkanoate is a terpolymer or a binary copolymer; the binary copolymer comprises a first monomer unit and a second monomer unit, the first monomer unit is 3-hydroxybutyric acid, and the molar percentage of the first monomer unit in the binary copolymer is less than 90%.

[0009] The agricultural product coating material provided by the present invention can be used for the production of coated agricultural products. During the coating process, the coating material can be formed at a temperature of 40-70°C (maximum not exceeding 100°C) instead of using the traditional high-temperature film-forming process, thereby helping to reduce or avoid the adverse effects of high temperature on the contents of the coated agricultural products (such as seeds, organic fertilizers, agricultural drugs, etc.). The present invention provides a polyhydroxyalkanoate-based aqueous emulsion coating material, which can achieve protection and sustained release effects within the validity period, and can be degraded in the natural environment after the validity period, without polluting the environment.

[0010] It should be noted that the polyhydroxyalkanoate of the present invention may be a single composition or a blended composition (ie, a mixture).

[0011] In some embodiments of the present invention, the polyhydroxyalkanoate is a terpolymer comprising three polymerizable monomers.

[0012] In other embodiments of the present invention, the polyhydroxyalkanoate is a binary copolymer comprising two polymerizable monomers.

[0013] The polymerizable monomers are divided into short chains (3-5 carbons) and medium chains (6-14 carbons) according to the number of carbon atoms. Specifically, the polymerizable monomers can be selected from 3-hydroxypropionic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 5-hydroxyvaleric acid, 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid or 3-hydroxydodecanoic acid.

[0014] In the present invention, the binary copolymer comprises a first monomer unit and a second monomer unit, wherein the first monomer unit is 3-hydroxybutyric acid, and the second monomer unit is preferably selected from 3-hydroxyvaleric acid, 3-hydroxyhexanoic acid or 4-hydroxybutyric acid.

[0015] More preferably, the molar percentage of the second monomer unit in the binary copolymer is greater than 10% and less than 30%.

[0016] More preferably, the molar percentage of the second monomer unit in the binary copolymer is any value greater than 10% and less than or equal to 30%, for example, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%.

[0017] Further preferably, in the present invention, the ternary copolymer is selected from P3HB4HB3HV and / or P3HB4HB5HV; or, the binary copolymer is selected from at least one of P34HB, PHBHHx or PHBV.

[0018] The present invention does not particularly limit the specific source of the polyhydroxyalkanoate, and any polyhydroxyalkanoate prepared by conventional preparation methods in the art or any polyhydroxyalkanoate obtained from general commercial channels in the art may be used.

[0019] The present invention does not particularly limit the specific types and sources of the emulsifiers, leveling agents and wetting agents. Any emulsifiers, leveling agents and wetting agents that can be used in agricultural product production and are available from conventional commercial channels in the field can be used.

[0020] In a more specific embodiment provided by the present invention:

[0021] The emulsifier of the agricultural product coating material is preferably at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene oleate, polyoxyethylene ether ammonium sulfate, and sodium dodecyl diphenyl ether disulfonate. The polyoxyethylene sorbitan fatty acid ester can be selected from Tween 20 from commercial sources.

[0022] And / or, the leveling agent of the agricultural product coating material is preferably at least one of polyether siloxane, modified polysiloxane, polydimethylsiloxane, polymethyl alkyl siloxane, acrylic acid, and cellulose. Among them, the polyether siloxane can be selected from Digo 432 (multifunctional leveling agent, a mixture containing polyether siloxane) from commercial sources.

[0023] And / or, the wetting agent of the agricultural product coating material is preferably at least one of potassium dodecyl phosphate, sodium dodecyl polyoxyethylene ether sulfate, sodium lauroyl acid, sodium α-olefin sulfonate, and alkyl polyoxyethylene ether.

[0024] In a second aspect, the present invention provides a coated agricultural product, comprising the aforementioned agricultural product coating material with sustained-release function, and also comprising contents.

[0025] In the present invention, the contents may be selected from seeds, medicines or fertilizers.

[0026] The coated agricultural product provided by the present invention can form a uniform coating film based on a simple coating method, which has a good protection and sustained release effect. The coated agricultural product provided by the present invention has a coating, and since the traditional high-temperature film formation is not required during the production and preparation process, the contents will not be affected by high temperature (or the impact is very small), which helps to improve the quality of the coated agricultural product. At the same time, the contents of the coated agricultural product provided by the present invention have better heat resistance under the protection of the coating, and have obvious advantages over similar products during transportation and storage.

[0027] The present invention does not particularly limit the specific types of the seeds, medicines or fertilizers. The seeds, medicines or fertilizers commonly used in agricultural production in the art can be used as the contents of the coated agricultural products of the present invention.

[0028] In a more specific embodiment provided by the present invention:

[0029] The seeds are preferably corn, wheat, peanut, cotton or soybean.

[0030] The drug is preferably an insecticide, a fungicide or a growth regulator.

[0031] The fertilizer is preferably phosphate fertilizer, potash fertilizer, bacterial fertilizer or nitrogen fertilizer.

[0032] In a third aspect, the present invention provides a preparation method for the aforementioned coated agricultural product, comprising the following steps:

[0033] S1, after dispersing the polyhydroxyalkanoate in water, adding an emulsifier, a leveling agent and a wetting agent, and dispersing again to obtain an aqueous emulsion of a coating material;

[0034] S2, soaking the content in the aqueous emulsion of the coating material, filtering, and obtaining a coated object;

[0035] S3, evaporating the surface moisture of the coating to obtain the coated agricultural product.

[0036] The preparation method of the present invention first disperses the polyhydroxyalkanoate in water, then adds an emulsifier, a leveling agent and a wetting agent, and disperses it again, so that each additive is evenly dispersed and coated on the surface of the polyhydroxyalkanoate to form a stable oil-in-water dispersion system, and obtains an aqueous emulsion of the coating material.

[0037] Preferably, in the coating material aqueous emulsion in step S1, the concentration of the polyhydroxyalkanoate is 20-45wt%, more preferably 25-35%.

[0038] Preferably, in the aqueous emulsion of the coating material in step S1, the particle size of the polyhydroxyalkanoate is ≤3 microns, more preferably ≤1 micron.

[0039] Preferably, in the coating material aqueous emulsion in step S1, the added amount of the emulsifier is 0.1-1%, preferably 0.1-0.5%; the added amount of the leveling agent is 0.1-1%, preferably 0.1-0.5%; the added amount of the wetting agent is 0.1-1%, preferably 0.1-0.5%.

[0040] In a specific embodiment of the present invention, the content is urea. The polyhydroxyalkanoate is P34HB-15% 4HB (poly 3-hydroxybutyric acid-4-hydroxybutyric acid copolyester, 4-hydroxybutyric acid copolyester has a molar content of 15%), and its concentration is any value between 25% and 35%, for example, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%.

[0041] In another specific embodiment of the present invention, the content is bacterial fertilizer. The polyhydroxyalkanoate is P34HB3HV (4HB14%, 3HV3%) (poly 3-hydroxybutyric acid-4-hydroxybutyric acid-3-hydroxyvaleric acid trimer, 4-hydroxybutyric acid molar content 14%, 3-hydroxyvaleric acid molar content 3%), and its concentration is any value in the range of 25%-35%, for example, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%.

[0042] Further preferably:

[0043] In a specific embodiment of the present invention, the content is urea. The polyhydroxyalkanoate is P3HB4HB3HV (3-hydroxybutyric acid content 79-81%, 4-hydroxybutyric acid content 14-16%, 3-hydroxyvaleric acid content 4-6%), and its concentration is 28%-35%; the emulsifier is sodium dodecyl sulfate, and its concentration is 0.1%-0.5%. The leveling agent is Digo 432, and its concentration is 0.1%-0.5%. The wetting agent is sodium lauroyl acid, and its concentration is 0.1%-0.5%.

[0044] In another specific embodiment of the present invention, the content is urea. The polyhydroxyalkanoate is P34HB (3-hydroxybutyric acid content 78-82%, 4-hydroxybutyric acid content 18-22%), and its concentration is 28-38wt%; the emulsifier is Tween 20, and its concentration is 0.1%-0.5%. The leveling agent is modified polysiloxane, and its concentration is 0.1%-0.5%. The wetting agent is sodium dodecyl polyoxyethylene ether sulfate, and its concentration is 0.1%-0.5%.

[0045] The preparation method provided by the invention relates to a dispersion process.

[0046] Specifically, the present invention can be dispersed by using a commonly used dispersion method in the art such as mechanical stirring or ultrasonic dispersion.

[0047] Preferably, after adding the emulsifier, the leveling agent and the wetting agent, the present invention adopts mechanical stirring, the rotation speed is controlled at 2000-3000 rpm, and the dispersion time is controlled at 25-35 min.

[0048] After obtaining the coating material aqueous emulsion, the preparation method of the present invention places the content in the coating material aqueous emulsion and soaks it, and filters it to obtain the coated object. The soaking time is 1-5 minutes, preferably 2-4 minutes, and more preferably 3 minutes. The above soaking time will not cause adverse effects on the content (content dissolving in water or absorbing too much water to cause loss or sprouting, etc.), and the aqueous emulsion can completely infiltrate the surface of the content to form a complete coating film, thereby achieving sustained release and protection effects.

[0049] After obtaining the coated object, the preparation method of the present invention evaporates the surface moisture of the coated object to obtain the coated agricultural product.

[0050] In the present invention, the evaporation temperature is preferably 30-100° C., more preferably 40-70° C., more preferably 50-60° C. The evaporation time is preferably 1-10 min, more preferably 3-8 min, more preferably 4-6 min.

[0051] The present invention does not particularly limit the specific equipment for the evaporation and drying, and any evaporation and drying equipment conventionally used for agricultural product processing in the art can be used.

[0052] The coated agricultural products obtained by the above preferred implementation have better product quality (long release cycle of fertilizer and bacterial fertilizer; vigorous growth of corn seeds, etc.) and heat resistance.

[0053] The preparation method provided by the invention has simple production process, low cost, is easy for industrial production, and has broad application prospects.

[0054] Beneficial effects:

[0055] The present invention provides an agricultural product coating material, coated agricultural product and preparation method. The agricultural product coating material comprises the following components in parts by weight: 20-45 parts of polyhydroxyalkanoate, 0.1-1 parts of emulsifier, 0.1-1 parts of leveling agent and 0.1-1 parts of wetting agent; the polyhydroxyalkanoate is a terpolymer or a dipolymer; the dipolymer comprises a first monomer unit and a second monomer unit, the first monomer unit is 3-hydroxybutyric acid, and the molar percentage of the first monomer unit in the dipolymer is less than 90%. The agricultural product coating material provided by the present invention can be used for the production of coated agricultural products. During the coating process, the coating material can be formed at a temperature of 40-70°C (maximum not exceeding 100°C) instead of using the traditional high-temperature film-forming process, thereby helping to reduce or avoid the adverse effects of high temperature on the contents (such as seeds, organic fertilizers, agricultural drugs, etc.) in the coated agricultural products. The agricultural product coating material provided by the present invention is suitable for coating various agricultural products (such as seeds, fertilizers, drugs, etc.), and can achieve the purpose of protection and sustained release. The coating material provided by the present invention is used for coating agricultural products. After coating, the obtained coated agricultural products have high heat resistance. In addition, the agricultural product coating material provided by the present invention is environmentally friendly and can be degraded in the soil environment without causing environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be described below.

[0057] Figure 1 This is the nitrogen release curve of the coated agricultural product-slow-release urea obtained in Example 1.

[0058] Figure 2 This is the nitrogen release curve of the coated agricultural product-slow-release urea obtained in Example 2.

[0059] Figure 3 This is the nitrogen release curve of the coated agricultural product-slow-release urea obtained in Comparative Example 1.

[0060] Figure 4 This is the nitrogen release curve of the coated agricultural product-slow-release urea obtained in Comparative Example 2. DETAILED DESCRIPTION

[0061] The term "include" or "comprising" in the present invention is an open description containing the specified components or steps described, and other specified components or steps that will not be substantially affected.

[0062] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "specific implementations", or "some specific implementations" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0064] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0066] The Chinese full names of the English abbreviations appearing in this article are as follows:

[0067] PHA: Polyhydroxyalkanoate

[0068] PHBV: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

[0069] P3HB4HB or P34HB: poly(3-hydroxybutyrate-co-4-hydroxybutyrate)

[0070] PHBHHx: Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)

[0071] P3HB4HB3HV: poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-3-hydroxyvalerate)

[0072] P3HB4HB5HV: poly(3-hydroxybutyrate-co-4-hydroxybutyrate-co-5-hydroxyvalerate).

[0073] Example 1

[0074] This embodiment provides an agricultural product coating material, and its specific formula is as follows:

[0075] 30 parts by mass of P3HB4HB3HV (melting point 98°C, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 15%, 3-hydroxyvaleric acid content 5%), 0.1 parts by mass of sodium lauryl sulfate, 0.1 parts by mass of Digo 432 and 0.1 parts by mass of sodium lauroyl acid.

[0076] This embodiment also provides a coated agricultural product-slow-release urea based on the above agricultural product coating material, and its specific formula is as follows:

[0077] 30 parts by mass of P3HB4HB3HV (melting point 98°C, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 15%, 3-hydroxyvaleric acid content 5%), 0.1 parts by mass of sodium dodecyl sulfate, 0.1 parts by mass of Digo 432, 0.1 parts by mass of sodium lauroyl acid and 300 parts by mass of urea granules.

[0078] This embodiment also provides a method for preparing the above-mentioned coated agricultural product-slow-release urea, which is as follows:

[0079] Weigh 30 parts by mass of P3HB4HB3HV (melting point 98°C, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 15%, 3-hydroxyvaleric acid content 5%) powder (particle size 1 micron), add it to 69.7 parts by mass of water, stir at a speed of 2000rpm, and disperse for 30 minutes to evenly disperse the polyhydroxyalkanoate in water. Then add 0.1 parts by mass of sodium dodecyl sulfate, 0.1 parts by mass of Digo 432, and 0.1 parts by mass of sodium lauroyl acid, stir at a speed of 2000rpm, and disperse for 30 minutes to evenly disperse the additives to form a colloidal and evenly dispersed aqueous emulsion.

[0080] Urea particles were used as the content and were immersed in water emulsion for 3 minutes to make a layer of water emulsion attached to the surface of the urea particles. The urea particles attached with water emulsion were placed in a fluidized bed drying oven at 50°C and baked for 5 minutes to evaporate the surface water and form a protective film, thus obtaining the coated agricultural product - slow-release urea.

[0081] The slow-release effect of the obtained coated agricultural product-slow-release urea was tested:

[0082] 10g of slow-release urea was placed in 100g of water and soaked at 23 degrees Celsius. The N content increase gradient in the water was measured on the 1st, 3rd, 5th, 7th, 14th, 30th, 60th and 90th day of soaking, and the nitrogen release data was recorded and the nitrogen release curve was drawn. The results are shown in Table 1 and Figure 1 shown.

[0083] Table 1 Nitrogen release

[0084]

[0085] Example 2

[0086] This embodiment provides an agricultural product coating material, and its specific formula is as follows:

[0087] 30 parts by mass of P34HB (melting point 136° C., 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 20%), 0.5 parts by mass of Tween 20, 0.5 parts by mass of modified polysiloxane and 0.5 parts by mass of sodium lauryl polyoxyethylene ether sulfate.

[0088] This embodiment also provides a coated agricultural product-slow-release urea based on the above agricultural product coating material, and its specific formula is as follows:

[0089] 30 parts by mass of P34HB (melting point 136°C, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 20%), 0.5 parts by mass of Tween 20, 0.5 parts by mass of modified polysiloxane, 0.5 parts by mass of sodium lauryl polyoxyethylene ether sulfate and 300 parts by mass of urea granules.

[0090] This embodiment also provides a method for preparing the above-mentioned coated agricultural product-slow-release urea, which is as follows:

[0091] Weigh 30 parts by mass of P34HB (melting point 136°C, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 320%) powder (particle size 0.7 micron), add it to 68.5 parts by mass of water, stir at 3000 rpm, and disperse for 30 minutes to evenly disperse the polyhydroxyalkanoate in water. Then add 0.5 parts by mass of Tween 20, 0.5 parts by mass of modified polysiloxane, and 0.5 parts by mass of sodium dodecyl polyoxyethylene ether sulfate, stir at 3000 rpm, and disperse for 30 minutes to evenly disperse the additives to form a colloidal and evenly dispersed aqueous emulsion.

[0092] Urea particles were used as the content and were immersed in water emulsion for 3 minutes to make a layer of water emulsion attached to the surface of the urea particles. The urea particles attached with water emulsion were placed in a fluidized bed drying oven at 60°C and baked for 5 minutes to evaporate the surface water and form a protective film, thus obtaining the coated agricultural product - slow-release urea.

[0093] The slow-release effect of the obtained coated agricultural product-slow-release urea was tested:

[0094] 10g of slow-release urea was placed in 100g of water and soaked at 23 degrees Celsius. The N content increase gradient in the water was measured on the 1st, 3rd, 5th, 7th, 14th, 30th, 60th and 90th day of soaking, and the nitrogen release data was recorded to draw a nitrogen release curve. The results are shown in Table 2 and Figure 2 shown.

[0095] Table 2 Nitrogen release

[0096]

[0097]

[0098] Example 3

[0099] This embodiment provides an agricultural product coating material, and its specific formula is as follows:

[0100] 30 parts by mass of P34HB (melting point 136° C., 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 20%), 0.5 parts by mass of Tween 20, 0.5 parts by mass of modified polysiloxane and 0.5 parts by mass of sodium lauryl polyoxyethylene ether sulfate.

[0101] This embodiment also provides a coated agricultural product based on the above agricultural product coating material - coated corn seeds, the specific formula of which is as follows:

[0102] 30 parts by mass of P34HB (melting point 136°C, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 20%), 0.5 parts by mass of Tween 20, 0.5 parts by mass of modified polysiloxane, 0.5 parts by mass of sodium lauryl polyoxyethylene ether sulfate and 300 parts by mass of urea granules.

[0103] This embodiment also provides a method for preparing the above-mentioned coated agricultural product-coated corn seeds, which is as follows:

[0104] Weigh 30 parts by mass of P34HB (melting point 136°C, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 320%) powder (particle size 0.7 micron), add it to 68.5 parts by mass of water, stir at 3000 rpm, and disperse for 30 minutes to evenly disperse the polyhydroxyalkanoate in water. Then add 0.5 parts by mass of Tween 20, 0.5 parts by mass of modified polysiloxane, and 0.5 parts by mass of sodium dodecyl polyoxyethylene ether sulfate, stir at 3000 rpm, and disperse for 30 minutes to evenly disperse the additives to form a colloidal and evenly dispersed aqueous emulsion.

[0105] Corn seeds were used as the content and soaked in water emulsion for 3 minutes to make a layer of water emulsion attached to the surface of the corn seeds. The corn seeds attached with water emulsion were placed in a fluidized bed drying oven at 60°C and baked for 5 minutes to evaporate the surface moisture and form a protective film, thus obtaining coated agricultural products - coated corn seeds.

[0106] The germination effect of the obtained coated agricultural product - corn seeds was tested:

[0107] Thirty coated corn seeds were taken, and the germination potential was counted on the fourth day, the germination rate was counted on the seventh day, and the root length, plant height, aboveground dry weight and underground dry weight were counted on the fifteenth day. The results are shown in Table 3, where the root length, plant height, aboveground dry weight and underground dry weight index data are average values.

[0108] Table 3 Seed germination and growth data

[0109]

[0110] Comparative Example 1

[0111] This comparative example provides a coated agricultural product-slow-release urea. The coated agricultural product-slow-release urea uses polyethylene (PE) as a coating material and urea as a content. The preparation method of the coated agricultural product-slow-release urea is as follows:

[0112] 10 parts by mass of PE (melting point 120° C.) was heated at 160° C. for 120 minutes and dissolved in 100 parts by mass of decalin solvent.

[0113] 300 parts by mass of urea granules were taken.

[0114] This embodiment also provides a method for preparing the above-mentioned coated agricultural product-slow-release urea, which is as follows:

[0115] 10 parts by mass of PE (melting point 120° C.) was weighed and added to 100 parts by mass of decalin solvent, stirred at 2000 rpm, heated to 160° C., and dispersed for 120 min to fully dissolve.

[0116] Urea particles were used as the content and were immersed in PE solution for 3 minutes to make a layer of PE solution attached to the surface of the urea particles. The urea particles attached with PE solution were placed in a fluidized bed drying oven at 50°C and baked for 5 minutes to evaporate the solvent on the surface and form a protective film, thus obtaining the coated agricultural product - slow-release urea.

[0117] The slow-release effect of the obtained coated agricultural product-slow-release urea was tested:

[0118] 10g of slow-release urea was placed in 100g of water and soaked at 23 degrees Celsius. The N content increase gradient in the water was measured on the 1st, 3rd, 5th, 7th, 14th, 30th, 60th and 90th days of soaking, the nitrogen release data was recorded, and the nitrogen release curve was drawn.

[0119] The slow-release effect of the obtained coated agricultural product-slow-release urea was tested:

[0120] 10g of slow-release urea was placed in 100g of water and soaked at 23 degrees Celsius. The N content increase gradient in the water was measured on the 1st, 3rd, 5th, 7th, 14th, 30th, 60th and 90th day of soaking, and the nitrogen release data was recorded to draw a nitrogen release curve. The results are shown in Table 4 and Figure 3 shown.

[0121] Table 4 Nitrogen release

[0122] Days(D) Nitrogen release (%) 1 3.22 3 6.93 5 10.57 7 16.06 14 28.51 30 59.42 60 92.54 90 98.86

[0123] Comparative Example 2

[0124] This comparative example provides a coated agricultural product-slow-release urea. The coated agricultural product-slow-release urea uses an acrylic acid aqueous solution as a coating material and urea as a content. The preparation method of the coated agricultural product-slow-release urea is as follows:

[0125] Weigh 100 g of acrylic acid aqueous emulsion with a solid content of 30%.

[0126] Urea particles were soaked in acrylic acid emulsion for 3 minutes to adhere a layer of acrylic acid emulsion on the surface of the urea particles. The urea particles with acrylic acid emulsion were placed in a fluidized bed drying oven at 60°C and baked for 5 minutes to evaporate the surface water and form a protective film, thus obtaining the coated agricultural product - slow-release urea.

[0127] The slow-release effect of the obtained coated agricultural product-slow-release urea was tested:

[0128] 10g of slow-release urea was placed in 100g of water and soaked at 23 degrees Celsius. The N content increase gradient in the water was measured on the 1st, 3rd, 5th, 7th, 14th, 30th, 60th and 90th day of soaking, and the nitrogen release data was recorded to draw a nitrogen release curve. The results are shown in Table 5 and Figure 4 shown.

[0129] Table 5 Nitrogen release

[0130] Days(D) Nitrogen release (%) 1 2.82 3 6.57 5 10.19 7 15.7 14 28.15 30 59.00 60 92.18 90 98.5

[0131] Comparative Example 3

[0132] Uncoated corn seeds, test the germination effect of corn seeds:

[0133] Thirty uncoated corn seeds were taken, and the germination potential was counted on the fourth day, the germination rate was counted on the seventh day, and the root length, plant height, aboveground dry weight and underground dry weight were counted on the fifteenth day. The results are shown in Table 6, where the root length, plant height, aboveground dry weight and underground dry weight index data are average values.

[0134] Table 6 Seed germination and growth data

[0135]

[0136]

[0137] The above-mentioned embodiments only express several implementation methods of the present invention, which is convenient for understanding the technical solution of the present invention in detail, but it cannot be understood as limiting the scope of the invention patent protection. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. Agricultural product coating material, characterized in that: The invention comprises the following components in parts by weight: 20-45 parts of polyhydroxyalkanoate, 0.1-1 part of emulsifier, 0.1-1 part of leveling agent and 0.1-1 part of wetting agent; the polyhydroxyalkanoate is a terpolymer or a binary copolymer; the binary copolymer comprises a first monomer unit and a second monomer unit, the first monomer unit is 3-hydroxybutyric acid, and the molar percentage of the first monomer unit in the binary copolymer is less than 90%.

2. The agricultural product coating material according to claim 1, characterized in that: The binary copolymer comprises a first monomer unit and a second monomer unit, wherein the first monomer unit is 3-hydroxybutyric acid, and the second monomer unit is selected from 3-hydroxyvaleric acid, 3-hydroxyhexanoic acid or 4-hydroxybutyric acid; Preferably, the molar percentage of the second monomer unit in the binary copolymer is greater than 10% and less than 30%.

3. The agricultural product coating material according to claim 1 or 2, characterized in that: The terpolymer is selected from P3HB4HB3HV and / or P3HB4HB5HV; or, the binary copolymer is selected from at least one of P34HB, PHBHHx or PHBV.

4. Coated agricultural product, characterized in that: The agricultural product coating material comprises the agricultural product coating material according to any one of claims 1 to 3, and also comprises contents, wherein the contents are seeds, medicines or fertilizers.

5. The coated agricultural product according to claim 4, characterized in that: The emulsifier of the agricultural product coating material is selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene oleate, polyoxyethylene ether ammonium sulfate, and sodium dodecyl diphenyl ether disulfonate.

6. The coated agricultural product according to claim 4 or 5, characterized in that: The leveling agent of the agricultural product coating material is selected from at least one of polyether siloxane, modified polysiloxane, polydimethylsiloxane, polymethyl alkyl siloxane, acrylic acid and cellulose.

7. The coated agricultural product according to any one of claims 4 to 6, characterized in that: The wetting agent of the agricultural product coating material is selected from at least one of potassium dodecyl phosphate, sodium dodecyl polyoxyethylene ether sulfate, sodium lauroyl acid, sodium α-olefin sulfonate, and alkyl polyoxyethylene ether.

8. The method for preparing the coated agricultural product according to any one of claims 4 to 7, characterized in that: The steps include: S1, dispersing the polyhydroxyalkanoate in water, adding an emulsifier, a leveling agent and a wetting agent, and dispersing again to obtain an aqueous emulsion of a coating material; S2, soaking the content in the aqueous emulsion of the coating material, filtering, and obtaining a coated object; S3, evaporating the surface moisture of the coating to obtain the coated agricultural product.

9. The preparation method according to claim 8, characterized in that: In the coating material aqueous emulsion in step S1, the dispersion concentration of the polyhydroxyalkanoate is 20-45wt%; and / or, in the aqueous emulsion of the coating material in step S1, the particle size of the polyhydroxyalkanoate is ≤3 μm; And / or, the soaking time in step S2 is 1-5 min, preferably 2-4 min, and more preferably 3 min.

10. The preparation method according to claim 8 or 9, characterized in that: In the aqueous emulsion of the coating material in step S1, the polyhydroxyalkanoate is poly 3-hydroxybutyric acid-4-hydroxybutyric acid-3-hydroxyvaleric acid copolyester, and the concentration is 28-35wt%; the emulsifier is sodium dodecyl sulfate, and the concentration is 0.1-0.5wt%; the leveling agent is Digo 432, and the concentration is 0.1-0.5wt%; the wetting agent is sodium lauroyl acid, and the concentration is 0.1-0.5wt%.

11. The preparation method according to claim 8 or 9, characterized in that: In the aqueous emulsion of the coating material in step S1, the polyhydroxyalkanoate is poly 3-hydroxybutyric acid-4-hydroxybutyric acid copolyester with a concentration of 28-35wt%; the emulsifier is Tween 20 with a concentration of 0.1-0.5wt%; the leveling agent is modified polysiloxane with a concentration of 0.1-0.5wt%; and the wetting agent is sodium dodecyl polyoxyethylene ether sulfate with a concentration of 0.1-0.5wt%.

12. The preparation method according to any one of claims 8 to 11, characterized in that: The temperature of the evaporation to dryness in step S3 is 30-100°C, preferably 40-70°C, more preferably 50-60°C.

Images