Coated agricultural product, coated agricultural product and method of preparation

Abstract

The present application relates to the technical field of agricultural product processing, and particularly relates to an agricultural product coating material, a coated agricultural product and a preparation method. The present application uses polyhydroxyalkanoate with specific performance as the main coating material for coating agricultural products. In the coating process, the traditional high-temperature film forming process is not used, but only needs to be formed at a temperature of 40-70 DEG C, thereby helping to reduce or avoid the adverse effects of high temperature on the contents (such as seeds, organic fertilizers, agricultural drugs, etc.) of the coated agricultural products. The agricultural product coating material provided by the present application is suitable for coating various agricultural products (such as seeds, fertilizers, drugs, etc.), and can achieve the purposes of protection and slow release. The coating material provided by the present application is used for agricultural product coating, and the obtained coated agricultural product has high heat resistance after coating. In addition, the agricultural product coating material provided by the present application is environmentally friendly and can be degraded in the soil environment, without causing environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of agricultural product processing technology, and in particular to an agricultural product coating material, coated agricultural products, and a preparation method thereof. Background Technology

[0002] Agricultural product coating technology mainly refers to the use of coatings to protect or slow-release agricultural products such as seeds, fertilizers, and pesticides. Common coating materials include polyethylene (PE) and acrylic acid. PE coating materials typically use organic solvents to prepare solutions before coating, which poses a significant environmental pollution risk. Acrylic acid coatings are usually prepared using aqueous emulsions and do not involve organic solvents. However, like PE coating materials, acrylic acid emulsion coatings are non-biodegradable. After disintegration, both PE and acrylic coating materials remain in the soil, forming microplastics that enter groundwater, potentially causing soil compaction and reduced crop yields.

[0003] Polyhydroxyalkanoates (PHAs) are a general term for biopolymer polyesters, including monomers and copolymers. With the development of synthetic biology, microbially synthesized PHA copolymers are further classified into random copolymers and block copolymers. More than 100 different monomers have been reported, most of which are 3-hydroxy fatty acids with chain lengths of 3-14 carbon atoms. Due to the wide variety of PHA monomers, there are significant differences in the physicochemical properties among different PHAs.

[0004] As a biosynthesized thermoplastic polymer, polyhydroxyalkanoates (PHA) typically exhibit good biodegradability and biocompatibility, and are considered environmentally friendly. Therefore, researchers have explored using PHA as a coating material for agricultural products. However, existing PHAs usually require drying at temperatures above 120°C during coating, which may adversely affect the contents of the agricultural product coating.

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

[0006] To address the problems existing in the prior art, this invention provides an environmentally friendly, biodegradable agricultural product coating material, coated agricultural products, and a preparation method that meet usage requirements. The agricultural product coating material provided by this invention is suitable for coating various agricultural products (such as seeds, fertilizers, and pharmaceuticals), achieving the purposes of protection and slow release. The PHA coating material itself can degrade in the soil environment and will not pollute the environment. Furthermore, when using the coating material provided by this invention for agricultural product coating, the coating temperature is relatively low (not exceeding 100℃), which can effectively reduce the adverse effects of high temperatures on the contents. In addition, after coating, the resulting coated agricultural products exhibit high 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 parts of emulsifier, 0.1-1 parts of leveling agent, and 0.1-1 parts of wetting agent; wherein the polyhydroxyalkanoate is a terpolymer or a binary copolymer; wherein the binary copolymer comprises a first monomer unit and a second monomer unit, the first monomer unit being 3-hydroxybutyric acid, and the molar percentage of the first monomer unit in the binary copolymer being <90%.

[0009] The agricultural product coating material provided by this invention can be used in the production of coated agricultural products. During the coating process, the coating material does not require traditional high-temperature film-forming processes; instead, it only needs a temperature of 40-70℃ (maximum not exceeding 100℃) to form a film. This helps to reduce or avoid the adverse effects of high temperatures on the contents of the coated agricultural products (such as seeds, organic fertilizers, agricultural pesticides, etc.). This invention provides an aqueous emulsion coating material based on polyhydroxyalkanoates, which can achieve protective and slow-release effects within its shelf life, and can degrade in the natural environment after its shelf life without polluting the environment.

[0010] It should be noted that the polyhydroxy fatty acid ester described in this invention can be a single component or a blend (i.e., a mixture).

[0011] In some embodiments of the present invention, the polyhydroxy fatty acid ester is a terpolymer containing three polymeric monomers.

[0012] In other embodiments of the present invention, the polyhydroxy fatty acid ester is a binary copolymer comprising two polymeric monomers.

[0013] The polymerizable monomers are classified into short-chain (3-5 carbons) and medium-to-long-chain (6-14 carbons) monomers based on the number of carbon atoms. Specifically, the polymerizable monomers may be selected from 3-hydroxypropionic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvalerate, 5-hydroxyvalerate, 3-hydroxyhexanoic acid, 3-hydroxyoctanoic acid, 3-hydroxynonanoic acid, 3-hydroxydecanoic acid, or 3-hydroxydodecanoic acid.

[0014] In this invention, the binary copolymer includes 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 3-hydroxyvalerate, 3-hydroxyhexanoic acid or 4-hydroxybutyric acid.

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

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

[0017] More preferably, in this invention, the terpolymer 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 specifically limit the source of the polyhydroxy fatty acid ester. Polyhydroxy fatty acid esters prepared by conventional methods in the art or those obtained from commercially available channels in the art are all acceptable.

[0019] This invention does not specifically limit the type and source of the emulsifier, leveling agent and wetting agent. Any emulsifier, leveling agent and wetting agent that can be used in agricultural production and is available from conventional commercial channels in the art is acceptable.

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

[0021] The emulsifier for the agricultural product coating material is preferably at least one selected from 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 may be selected from commercially available Tween 20.

[0022] And / or, the leveling agent of the agricultural product coating material is preferably at least one of polyether siloxane, modified polysiloxane, polydimethylsiloxane, polymethylalkylsiloxane, acrylic acid, and cellulose. The polyether siloxane may be selected from commercially available products such as Tigo 432 (a multifunctional leveling agent containing a mixture of polyether siloxanes).

[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 ether, sodium α-alkenyl sulfonate, and alkyl polyoxyethylene ether.

[0024] Secondly, the present invention provides a coated agricultural product, including the aforementioned agricultural product coating material with slow-release function, and also including contents.

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

[0026] The coated agricultural products provided by this invention can form a uniform coating film based on a simple coating method, effectively providing protection and slow-release effects. While possessing a coating, the contents of the coated agricultural products provided by this invention are not affected by high temperatures (or are minimally affected) during the production and preparation process because traditional high-temperature film formation is not required, thus contributing to improved quality. Simultaneously, the contents of the coated agricultural products provided by this invention, protected by the coating, exhibit better heat resistance properties, offering significant advantages over similar products during transportation and storage.

[0027] This invention does not specifically limit the categories of seeds, drugs, or fertilizers. Seeds, drugs, or fertilizers commonly used in agricultural production in the art can all be used as the contents of the coated agricultural products described in this invention.

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

[0029] The seeds are preferably corn, wheat, peanuts, cotton, or soybeans.

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

[0031] The fertilizer is preferably a phosphate fertilizer, potassium fertilizer, microbial fertilizer, or nitrogen fertilizer.

[0032] Thirdly, the present invention provides a preparation method for the aforementioned coated agricultural products, comprising the following steps:

[0033] S1. After dispersing the polyhydroxy fatty acid ester in water, an emulsifier, a leveling agent, and a wetting agent are added, and the mixture is dispersed again to obtain an aqueous emulsion of the coating material.

[0034] S2. Soak the contents in the aqueous emulsion of the coating material, filter, and obtain the coating material;

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

[0036] The preparation method of the present invention first disperses the polyhydroxy fatty acid ester in water, then adds an emulsifier, a leveling agent and a wetting agent, and disperses again, so that each auxiliary agent is uniformly dispersed and coated on the surface of the polyhydroxy fatty acid ester, forming a stable oil-in-water dispersion system, and obtaining an aqueous emulsion of coating material.

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

[0038] Preferably, in the aqueous emulsion of the coating material in step S1, the particle size of the polyhydroxy fatty acid ester is ≤3 micrometers, more preferably ≤1 micrometer.

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

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

[0041] In another specific embodiment of the present invention, the contents are microbial fertilizer. The polyhydroxyalkanoate is P34HB3HV (4HB 14%, 3HV 3%) (poly(3-hydroxybutyrate-4-hydroxybutyrate-3-hydroxyvalerate) trimer, with a 4-hydroxybutyrate molar content of 14% and a 3-hydroxyvalerate molar content of 3%), and its concentration is any value between 25% and 35%, for example 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, and 35%.

[0042] Further preferred:

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

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

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

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

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

[0048] The preparation method of this invention involves immersing the contents in an aqueous emulsion of the coating material after obtaining the emulsion, followed by filtration to obtain the coated material. The immersion time is 1-5 minutes, preferably 2-4 minutes, and more preferably 3 minutes. This immersion time does not adversely affect the contents (such as loss due to water dissolution or excessive water absorption, or germination), and allows the emulsion to completely wet the surface of the contents, forming a complete coating film, thus achieving sustained release and protection.

[0049] The preparation method of the present invention involves evaporating the surface moisture of the coating material after obtaining the coating material to obtain the coated agricultural product.

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

[0051] The present invention does not specifically limit the equipment used for steaming and drying; any steaming and drying equipment conventionally used in agricultural product processing in the art is acceptable.

[0052] The coated agricultural products obtained through the preferred embodiments described above have better product quality (longer release cycles of fertilizers and microbial fertilizers; vigorous growth of corn seeds, etc.) and better heat resistance.

[0053] The preparation method provided by this invention has a simple production process, low cost, and is easy to industrialize, and has broad application prospects.

[0054] Beneficial effects:

[0055] This invention provides an agricultural product coating material, coated agricultural products, and a preparation method thereof. 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 binary copolymer; the binary copolymer includes a first monomer unit and a second monomer unit, the first monomer unit being 3-hydroxybutyric acid, and the molar percentage of the first monomer unit in the binary copolymer is <90%. The agricultural product coating material provided by this invention can be used in the production of coated agricultural products. During the coating process, the traditional high-temperature film-forming process is not required; instead, film formation can be achieved at a temperature of only 40-70℃ (maximum not exceeding 100℃), thereby helping to reduce or avoid the adverse effects of high temperatures on the contents of the coated agricultural products (such as seeds, organic fertilizers, agricultural pesticides, etc.). The agricultural product coating material provided by this invention is suitable for coating various agricultural products (such as seeds, fertilizers, pesticides, etc.), achieving the purpose of protection and slow release. When the coating material provided by this invention is used to coat agricultural products, the resulting coated agricultural products exhibit high heat resistance. Furthermore, the agricultural product coating material provided by this invention is environmentally friendly, degradable in soil environments, and does not cause environmental pollution. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in this invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be described below.

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

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

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

[0060] Figure 4 The nitrogen release curve of the coated agricultural product-slow-release urea obtained in Comparative Example 2 is shown. Detailed Implementation

[0061] The terms “comprising” or “including” in this invention are open-ended descriptions that include the specified ingredients or steps described, as well as other specified ingredients or steps that do not materially affect them.

[0062] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "specific implementation," or "some specific implementations," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0064] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0065] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

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

[0067] PHA: Polyhydroxy fatty acid ester

[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 a coating material for agricultural products, the specific formulation of which is as follows:

[0075] 30 parts by weight of P3HB4HB3HV (melting point 98℃, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 15%, 3-hydroxyvalerate content 5%), 0.1 parts by weight of sodium dodecyl sulfate, 0.1 parts by weight of DIG 432 and 0.1 parts by weight of sodium lauroyl acid.

[0076] This embodiment also provides a coated agricultural product—slow-release urea—based on the above-mentioned agricultural product coating material, the specific formulation of which is as follows:

[0077] 30 parts by weight of P3HB4HB3HV (melting point 98℃, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 15%, 3-hydroxyvalerate content 5%), 0.1 parts by weight of sodium dodecyl sulfate, 0.1 parts by weight of DIG432, 0.1 parts by weight of sodium lauroyl acid and 300 parts by weight of urea granules.

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

[0079] Weigh 30 parts by weight of P3HB4HB3HV powder (melting point 98℃, 3-hydroxybutyric acid content 80%, 4-hydroxybutyric acid content 15%, 3-hydroxyvalerate content 5%) (particle size 1 micrometer), add it to 69.7 parts by weight of water, and stir at 2000 rpm for 30 minutes to ensure that the polyhydroxy fatty acid ester is uniformly dispersed in the water. Then add 0.1 parts by weight of sodium dodecyl sulfate, 0.1 parts by weight of DIG 432 and 0.1 parts by weight of sodium lauryl sulfate, and stir at 2000 rpm for 30 minutes to ensure that the additives are uniformly dispersed to form a colloidal, uniformly dispersed aqueous emulsion.

[0080] Using urea granules as the content, immerse them in an aqueous emulsion for 3 minutes to coat the surface of the urea granules with a layer of aqueous emulsion. Place the urea granules coated with aqueous emulsion in a fluidized bed drying oven at 50°C and bake for 5 minutes to evaporate the surface moisture and form a protective film, thus obtaining coated agricultural product - slow-release urea.

[0081] The sustained-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°C. The nitrogen content in the water was measured at increasing gradients on days 1, 3, 5, 7, 14, 30, 60, and 90 of soaking. Nitrogen release data were recorded, and nitrogen release curves were plotted. The results are shown in Table 1 and... Figure 1 As shown.

[0083] Table 1 Nitrogen Release

[0084]

[0085] Example 2

[0086] This embodiment provides a coating material for agricultural products, the specific formulation of which is as follows:

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

[0088] This embodiment also provides a coated agricultural product—slow-release urea—based on the above-mentioned agricultural product coating material, the specific formulation of which is as follows:

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

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

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

[0092] Using urea granules as the content, immerse them in an aqueous emulsion for 3 minutes to coat the surface of the urea granules with a layer of aqueous emulsion. Place the urea granules coated with aqueous emulsion in a fluidized bed drying oven at 60°C and bake for 5 minutes to evaporate the surface moisture and form a protective film, thus obtaining coated agricultural product - slow-release urea.

[0093] The sustained-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°C. The nitrogen content in the water was measured at increasing gradients on days 1, 3, 5, 7, 14, 30, 60, and 90 of soaking. Nitrogen release data were recorded, and nitrogen release curves were plotted. The results are shown in Table 2. Figure 2 As shown.

[0095] Table 2 Nitrogen Release

[0096]

[0097]

[0098] Example 3

[0099] This embodiment provides a coating material for agricultural products, the specific formulation of which is as follows:

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

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

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

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

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

[0105] Using corn seeds as the content, soak them in an aqueous emulsion for 3 minutes to coat the surface of the corn seeds with a layer of aqueous emulsion. Place the corn seeds coated with the aqueous emulsion in a fluidized bed drying oven at 60℃ and bake for 5 minutes to evaporate the surface moisture and form a protective film, thus obtaining coated agricultural product - coated corn seeds.

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

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

[0108] Table 3. Data on seed germination and growth

[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 the coating material and urea as the content. The specific preparation method of the coated agricultural product-slow-release urea is as follows:

[0112] 10 parts by weight of PE (melting point 120℃) were heated at 160℃ for 120 minutes and dissolved in 100 parts by weight of decahydronaphthalene solvent.

[0113] Take 300 parts by weight of urea granules.

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

[0115] Weigh 10 parts by weight of PE (melting point 120℃), add it to 100 parts by weight of decahydronaphthalene solvent, stir at 2000 rpm, heat to 160℃, and disperse for 120 minutes to fully dissolve.

[0116] Using urea granules as the content, immerse them in a PE solution for 3 minutes to coat the surface of the urea granules with a layer of PE solution. Place the urea granules coated with PE solution in a fluidized bed drying oven at 50°C and bake for 5 minutes to evaporate the solvent on the surface and form a protective film, thus obtaining coated agricultural product - slow-release urea.

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

[0118] Take 10g of slow-release urea and place it in 100g of water, then soak it at 23 degrees Celsius. On the 1st, 3rd, 5th, 7th, 14th, 30th, 60th and 90th days of soaking, measure the nitrogen content in the water at increasing gradients, record the nitrogen release data, and plot the nitrogen release curve.

[0119] The sustained-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°C. The nitrogen content in the water was measured at increasing gradients on days 1, 3, 5, 7, 14, 30, 60, and 90 of soaking. Nitrogen release data were recorded, and nitrogen release curves were plotted. The results are shown in Table 4. Figure 3 As shown.

[0121] Table 4 Nitrogen Release

[0122] Number of 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 aqueous acrylic acid solution as the coating material and urea as the content. The specific preparation method of the coated agricultural product-slow-release urea is as follows:

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

[0126] Using urea granules as the content, immerse them in an acrylic acid emulsion for 3 minutes to coat the surface of the urea granules with a layer of acrylic acid emulsion. Place the urea granules coated with acrylic acid emulsion in a fluidized bed drying oven at 60°C and bake for 5 minutes to evaporate the surface moisture and form a protective film, thus obtaining coated agricultural product - slow-release urea.

[0127] The sustained-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°C. The nitrogen content in the water was measured at increasing gradients on days 1, 3, 5, 7, 14, 30, 60, and 90 of soaking. Nitrogen release data were recorded, and nitrogen release curves were plotted. The results are shown in Table 5. Figure 4 As shown.

[0129] Table 5 Nitrogen Release

[0130] Number of 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 were used to test the germination rate of corn seeds:

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

[0134] Table 6. Data on Seed Germination and Growth

[0135]

[0136]

[0137] The embodiments described above are merely illustrative of several implementations of the present invention, designed to facilitate a detailed understanding of the technical solutions of the present invention. However, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A coating material for agricultural products, characterized in that, The product comprises the following components in parts by weight: 20-45 parts polyhydroxyalkanoate, 0.1-1 parts emulsifier, 0.1-1 parts leveling agent, and 0.1-1 parts wetting agent; wherein the polyhydroxyalkanoate is a terpolymer or a binary copolymer; wherein the binary copolymer comprises a first monomer unit and a second monomer unit, the first monomer unit being 3-hydroxybutyric acid, and the molar percentage of the first monomer unit in the binary copolymer being <90%; The second monomer unit is selected from 3-hydroxyvalerate, 3-hydroxyhexanoate, or 4-hydroxybutyric acid; the molar percentage of the second monomer unit in the binary copolymer is >10% and ≤30%. The terpolymer contains 3-hydroxybutyric acid monomer units; The coating material is an aqueous emulsion.

2. The agricultural product coating material according to claim 1, characterized in that, 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.

3. Coated agricultural products, characterized in that, It includes a coating layer formed by the agricultural product coating material according to any one of claims 1-2, and also includes contents, said contents being seeds, drugs or fertilizers.

4. The coated agricultural product according to claim 3, characterized in that, The emulsifier for the agricultural product coating material is selected from at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyoxyethylene sorbitan fatty acid ester, oleic acid polyoxyethylene ester, polyoxyethylene ether ammonium sulfate, and sodium dodecyl diphenyl ether disulfonate.

5. The coated agricultural product according to claim 3 or 4, characterized in that, The leveling agent of the agricultural product coating material is selected from at least one of modified polysiloxane, polymethylalkylsiloxane, acrylic acid, and cellulose.

6. The coated agricultural product according to claim 5, characterized in that, The modified polysiloxane is a polyether siloxane; and / or, the polymethylalkyl siloxane is a polydimethyl siloxane.

7. The coated agricultural product according to claim 3, 4 or 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 ether, sodium α-alkenyl sulfonate, and alkyl polyoxyethylene ether.

8. The coated agricultural product according to claim 5, 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 ether, sodium α-alkenyl sulfonate, and alkyl polyoxyethylene ether.

9. The method for preparing coated agricultural products according to any one of claims 3-8, characterized in that, Includes the following steps: S1. Disperse the polyhydroxy fatty acid ester in water, add emulsifier, leveling agent and wetting agent, and disperse again to obtain a water emulsion of coating material; S2. Soak the contents in the aqueous emulsion of the coating material, filter, and obtain the coating material; S3. Evaporate the surface moisture of the coating to obtain the coated agricultural product.

10. The preparation method according to claim 9, characterized in that, In the aqueous emulsion of the coating material described in step S1, the dispersion concentration of the polyhydroxyalkanoate is 20-45 wt%. And / or, in the aqueous emulsion of the coating material described in step S1, the particle size of the polyhydroxy fatty acid ester is ≤3 micrometers; And / or, the soaking time in step S2 is 1-5 minutes.

11. The preparation method according to claim 10, characterized in that, The soaking time is 2-4 minutes.

12. The preparation method according to claim 11, characterized in that, The soaking time is 3 minutes.

13. The preparation method according to any one of claims 9-12, characterized in that, In the aqueous emulsion of the coating material described in step S1, the polyhydroxyalkanoate is a poly(3-hydroxybutyrate-4-hydroxybutyrate-3-hydroxyvalerate) copolyester with a concentration of 28-35 wt%; the emulsifier is sodium dodecyl sulfate with a concentration of 0.1-0.5 wt%; the leveling agent is DIG432 with a concentration of 0.1-0.5 wt%; and the wetting agent is sodium lauroyl sulfate with a concentration of 0.1-0.5 wt%.

14. The preparation method according to any one of claims 9-12, characterized in that, In the aqueous emulsion of the coating material described in step S1, the polyhydroxy fatty acid ester is a poly(3-hydroxybutyrate-4-hydroxybutyrate) copolyester with a concentration of 28-35 wt%; the emulsifier is Tween 20 with a concentration of 0.1-0.5 wt%; the leveling agent is a modified polysiloxane with a concentration of 0.1-0.5 wt%; and the wetting agent is sodium dodecyl polyoxyethylene ether sulfate with a concentration of 0.1-0.5 wt%.

15. The preparation method according to any one of claims 9-12, characterized in that, The temperature for evaporation in step S3 is 30-100℃.

16. The preparation method according to claim 15, characterized in that, The temperature for evaporation in step S3 is 40-70℃.

17. The preparation method according to claim 16, characterized in that, The temperature for evaporation in step S3 is 50-60℃.

18. The preparation method according to claim 13, characterized in that, The temperature for evaporation in step S3 is 30-100℃.

19. The preparation method according to claim 14, characterized in that, The temperature for evaporation in step S3 is 30-100℃.

20. The preparation method according to claim 18 or 19, characterized in that, The temperature for evaporation in step S3 is 40-70℃.

21. The preparation method according to claim 20, characterized in that, The temperature for evaporation in step S3 is 50-60℃.

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