阅读说明：本技术 一种缓释作用微胶囊薄膜及其制备方法 (Sustained-release microcapsule film and preparation method thereof ) 是由 李威彤 于 2021-08-24 设计创作，主要内容包括：本发明公开了一种缓释作用微胶囊薄膜及其制备方法,涉及塑料技术领域。本发明使用废弃棉纤维作原料,用冷冻干燥技术制备纤维素气凝胶,对纤维素气凝胶进行疏水性改性,得预改性纤维素气凝胶,将氧化亚铜沉积到预改性纤维素气凝胶上,得改性纤维素气凝胶；将2-甲硫基-4,6-双异丙胺基均三氮苯溶于甲醇中,加固化剂得固化液,将固化液填充在改性纤维素气凝胶中,干燥后得预处理芯材,将预处理芯材粉碎后得到改性芯材；以三聚氰胺-尿素-羟基乙酸预聚物为壁材,对改性芯材进行包覆,得到改性微胶囊,加入到熔融的聚乙烯中进行混合,经过鼓吹、冷却步骤后制得缓释作用微胶囊薄膜。本发明制备的缓释作用微胶囊薄膜具有增肥、缓释、除草、不残留的效果。(The invention discloses a microcapsule film with a slow release effect and a preparation method thereof, and relates to the technical field of plastics. The method comprises the steps of preparing cellulose aerogel by using waste cotton fibers as raw materials and using a freeze drying technology, carrying out hydrophobic modification on the cellulose aerogel to obtain pre-modified cellulose aerogel, and depositing cuprous oxide on the pre-modified cellulose aerogel to obtain modified cellulose aerogel; dissolving 2-methylthio-4, 6-bis-isopropylamino sym-triazine in methanol, adding a curing agent to obtain a curing solution, filling the curing solution into modified cellulose aerogel, drying to obtain a pretreated core material, and crushing the pretreated core material to obtain a modified core material; the modified core material is coated by taking the melamine-urea-glycolic acid prepolymer as a wall material to obtain modified microcapsules, the modified microcapsules are added into molten polyethylene for mixing, and the microcapsule film with the slow release effect is prepared after blowing and cooling steps. The microcapsule film with slow release effect prepared by the invention has the effects of increasing fertilizer, slow release, weeding and no residue.)

1. The preparation method of the microcapsule film with the slow release effect is characterized in that the process flow of the microcapsule film with the slow release effect is as follows: the preparation method comprises the following steps of preparing cellulose aerogel, preparing pre-modified cellulose aerogel, preparing curing liquid, preparing modified core material, preparing modified microcapsule and preparing sustained-release microcapsule.

2. The method for preparing the microcapsule film with sustained release effect according to claim 1, comprising the following steps:

(1) crushing clean waste cotton fibers into small sections of 0.2mm to obtain crushed cellulose, dispersing the crushed cellulose in 7% sodium hydroxide solution to prepare 20mg/ml dispersion liquid I, performing ultrasonic dispersion for 10min at the frequency of 50Hz, diluting the dispersion liquid I into 10mg/ml dispersion liquid II by using 7% sodium hydroxide solution, pouring the dispersion liquid II into a freeze-drying mold, adjusting a freeze-drying machine into a freezing mode, cooling and freezing, adjusting the freeze-drying machine into a drying mode, vacuumizing to set the vacuum degree to 1Pa, heating the mold, preserving heat for a period of time, and naturally cooling to obtain a material a; adding the material a into a tubular heating furnace, raising the temperature to 500 ℃ in a mixed gas atmosphere consisting of hydrogen and argon, carrying out heat preservation reaction, and naturally cooling to obtain a material b; soaking the material b in a tetrahydrofuran solution with the concentration of 15%, then placing the material b into a dryer, sealing the dryer, placing the dryer into an air-blowing drying oven, heating to 90 ℃, starting reaction, raising the temperature of the air-blowing drying oven to 200 ℃ after the reaction is finished, carrying out constant-temperature reaction, naturally cooling, and then washing the product in deionized water until the washing liquid is neutral to obtain cellulose aerogel;

(2) placing cellulose aerogel in a closed dryer, simultaneously placing an open beaker containing methyltrichlorosilane with the mass 5 times that of the cellulose aerogel in the dryer, sealing the dryer at normal temperature for 24 hours to perform silanization reaction, and after the reaction is finished, placing the silanized cellulose aerogel in a vacuum drying oven at normal temperature to remove unreacted silane to prepare the pre-modified cellulose aerogel;

(3) soaking the pre-modified cellulose aerogel in a copper sulfate solution with the mass fraction of 2%, then soaking the pre-modified cellulose aerogel soaked in a copper persulfate solution in a sodium hydroxide solution with the pH value of 12, transferring the pre-modified cellulose aerogel soaked in the sodium hydroxide solution to 1% hydrazine hydrate, soaking in a normal temperature environment, and finally washing a product with deionized water until a washing solution is neutral to prepare the modified cellulose aerogel;

(4) dissolving 2-methylthio-4, 6-diisopropylamino sym-triazine in a methanol solvent, adding a curing agent vinyl triamine, and uniformly mixing to obtain a curing liquid;

(5) placing the modified cellulose gel in a mold, pouring curing liquid with the amount of 5 times that of the modified cellulose gel, sealing the mold, and carrying out vacuum drying on the interior of the mold, wherein the vacuum degree is-0.1 MPa, the drying temperature is 80 ℃, and the drying time is 5-6 hours, so as to obtain a pretreated core material; performing ball milling operation on the pretreated core material, taking deionized water as a grinding-aid solvent, wherein the ball-material ratio is 5: 3, the mass ratio of the pretreated core material to the deionized water is 3: 1, the particle size of the pretreated core material after ball milling is 900-1000 nm, and a modified core material is prepared;

(6) dispersing urea into a 30% formaldehyde solution, adding melamine, glycolic acid and an emulsifier sodium alkyl benzene sulfonate, adjusting the pH to 8.3, uniformly stirring to obtain a mixed solution I, placing the mixed solution I in a water bath with the constant temperature of 60 ℃, and stirring at the speed of 200r/min for 30-40 min to obtain a wall material solution; dispersing the modified core material into a 30% formaldehyde solution, uniformly stirring to obtain a second mixed solution, placing the second mixed solution in a 40 ℃ water bath, stirring at the speed of 200r/min, simultaneously dropwise adding a wall material solution at the dropping speed of 3 drops/s, reacting for 20-30 min, and then carrying out hot air drying on a reaction system at the drying temperature of 60-70 ℃ for 3-5 h to obtain modified microcapsules;

(7) dispersing the modified microcapsule in molten polyethylene 10 times the weight of the modified microcapsule, adding curing agent vinyl triamine 0.03 time the weight of the molten polyethylene, mixing, blowing, and naturally cooling to obtain the slow-release microcapsule film.

3. The preparation method of the microcapsule film with sustained release effect according to claim 2, wherein in the step (1), when the material a is prepared, the temperature of a refrigerator is reduced to-45 ℃, and the freezing time is 4-5 h; controlling the heating rate to be 1 ℃/h, heating to 30 ℃, and keeping the temperature for 24 h; and the volume ratio of hydrogen to argon in the preparation of the material b is 1: 9; the heating rate is 10 ℃/min, and the reaction time is 2-3 h; when the cellulose gel is prepared, the reaction time is 24 hours after the temperature is raised to 90 ℃; the reaction time is 30min at constant temperature.

4. The process for preparing a sustained-release microcapsule film according to claim 2, wherein in the step (2), the degree of vacuum of the vacuum drying oven is 1Pa, and the drying time is 24 hours.

5. The preparation method of the microcapsule film with the slow release effect according to claim 2, wherein in the step (3), the soaking time is 10-15 min, and the mass ratio of the modified cellulose aerogel to the copper sulfate solution to the sodium hydroxide solution to the hydrazine hydrate is 1: 6: 6: 6.

6. the method for preparing a microcapsule film with sustained release effect according to claim 2, wherein in the step (4), the mass ratio of the 2-methylthio-4, 6-diisopropylamino group sym-triazine solvent to the curing agent vinyl triamine is 1: 29: 1.3.

7. the method for preparing a microcapsule film with sustained release effect according to claim 2, wherein in the step (6), the mass ratio of urea to formaldehyde solution to melamine to glycolic acid to the emulsifier sodium alkylbenzenesulfonate is 1: 3: 1.2: 1: 0.1, the mass ratio of the modified core material to the formaldehyde solution is 1: 4; the mass ratio of the mixed solution II to the wall material solution is 1: 3.

8. the method for preparing a sustained-release microcapsule film according to claim 1, wherein the sustained-release microcapsule film prepared by the method for preparing a sustained-release microcapsule film comprises the following raw materials in parts by weight: 30-50 parts of modified core material, 100-200 parts of curing liquid, 90-150 parts of melamine-urea-glycolic acid prepolymer and 300-500 parts of polyethylene; the modified core material is prepared by processing waste cotton fibers; the curing liquid is prepared by dissolving 2-methylthio-4, 6-diisopropylamino sym-triazine in a methanol solvent and adding a curing agent of vinyl triamine.

Technical Field

The invention relates to the technical field of plastics, in particular to a microcapsule film with a slow release effect and a preparation method thereof.

Background

With the maturity and perfection of plastic mulching film covering technology, the variety of mulching films is continuously increased, functional mulching films are also appeared, and the method for preparing the functional mulching films at present mainly comprises the following steps. The second is to functional medicament spraying, coating or adopt the adhesive to adhere to the plastics plastic film, and this method has nevertheless made the homogeneity of medicament obtain certain promotion, but because the medicament can only be attached to the plastic film surface, the speed of medicine release is very fast, can't guarantee the medicine effect in later stage, has caused the waste to a certain extent. The third is that functional medicine and high molecular resin are first produced into mother particle, the mother particle is added into high molecular resin and blown to form film in common film forming mode. Therefore, it is necessary to develop a microcapsule film having a sustained release effect.

The microcapsule film with slow release effect has the effects of increasing fertilizer, slow release, weeding and no residue while ensuring the inherent performance of the microcapsule film.

Disclosure of Invention

The invention aims to provide a microcapsule film with slow release effect and a preparation method thereof, which are used for solving the problems in the prior art.

In order to solve the technical problems, the invention provides the following technical scheme: the preparation method of the microcapsule film with the slow release effect is characterized in that the process flow of the microcapsule film with the slow release effect is as follows:

the preparation method comprises the following steps of preparing cellulose aerogel, preparing pre-modified cellulose aerogel, preparing curing liquid, preparing modified core material, preparing modified microcapsule and preparing sustained-release microcapsule.

Further, the preparation method of the microcapsule film with the slow release effect is characterized by comprising the following specific steps:

(1) crushing clean waste cotton fibers into small sections of 0.2mm to obtain crushed cellulose, dispersing the crushed cellulose in 7% sodium hydroxide solution to prepare 20mg/ml dispersion liquid I, performing ultrasonic dispersion for 10min at the frequency of 50Hz, diluting the dispersion liquid I into 10mg/ml dispersion liquid II by using 7% sodium hydroxide solution, pouring the dispersion liquid II into a freeze-drying mold, adjusting a freeze-drying machine into a freezing mode, cooling and freezing, adjusting the freeze-drying machine into a drying mode, vacuumizing to set the vacuum degree to 1Pa, heating the mold, preserving heat for a period of time, and naturally cooling to obtain a material a; adding the material a into a tubular heating furnace, raising the temperature to 500 ℃ in a mixed gas atmosphere consisting of hydrogen and argon, carrying out heat preservation reaction, and naturally cooling to obtain a material b; soaking the material b in a tetrahydrofuran solution with the concentration of 15%, then placing the material b into a dryer, sealing the dryer, placing the dryer into an air-blowing drying oven, heating to 90 ℃, starting reaction, raising the temperature of the air-blowing drying oven to 200 ℃ after the reaction is finished, carrying out constant-temperature reaction, naturally cooling, and washing the product in deionized water until the washing liquid is neutral to obtain the cellulose aerogel;

(2) placing cellulose aerogel in a closed dryer, simultaneously placing an open beaker containing methyltrichlorosilane with the mass 5 times that of the cellulose aerogel in the dryer, sealing the dryer at normal temperature for 24 hours to perform silanization reaction, and after the reaction is finished, placing the silanized cellulose aerogel in a vacuum drying oven at normal temperature to remove unreacted silane to prepare the pre-modified cellulose aerogel;

(3) soaking the pre-modified cellulose aerogel in a copper sulfate solution with the mass fraction of 2%, then soaking the pre-modified cellulose aerogel soaked in a copper persulfate solution in a sodium hydroxide solution with the pH value of 12, transferring the pre-modified cellulose aerogel soaked in the sodium hydroxide solution to 1% hydrazine hydrate, soaking in a normal temperature environment, and finally washing a product with deionized water until a washing solution is neutral to prepare the modified cellulose aerogel;

(4) dissolving 2-methylthio-4, 6-diisopropylamino sym-triazine in a methanol solvent, adding a curing agent vinyl triamine, and uniformly mixing to obtain a curing liquid;

(5) placing the modified cellulose gel in a mold, pouring curing liquid with the amount of 5 times that of the modified cellulose gel, sealing the mold, and carrying out vacuum drying on the interior of the mold, wherein the vacuum degree is-0.1 MPa, the drying temperature is 80 ℃, and the drying time is 5-6 hours, so as to obtain a pretreated core material; performing ball milling operation on the pretreated core material, taking deionized water as a grinding-aid solvent, wherein the ball-material ratio is 5: 3, the mass ratio of the pretreated core material to the deionized water is 3: 1, the particle size of the pretreated core material after ball milling is 900-1000 nm, and a modified core material is prepared;

(6) dispersing urea into a 30% formaldehyde solution, adding melamine, glycolic acid and an emulsifier sodium alkyl benzene sulfonate, adjusting the pH to 8.3, uniformly stirring to obtain a mixed solution I, placing the mixed solution I in a water bath with the constant temperature of 60 ℃, and stirring at the speed of 200r/min for 30-40 min to obtain a wall material solution; dispersing the modified core material into a 30% formaldehyde solution, uniformly stirring to obtain a second mixed solution, placing the second mixed solution in a 40 ℃ water bath, stirring at the speed of 200r/min, simultaneously dropwise adding a wall material solution at the dropping speed of 3 drops/s, reacting for 20-30 min, and then carrying out hot air drying on a reaction system at the drying temperature of 60-70 ℃ for 3-5 h to obtain modified microcapsules;

(7) dispersing the modified microcapsule in molten polyethylene 10 times the weight of the modified microcapsule, adding curing agent vinyl triamine 0.03 time the weight of the molten polyethylene, mixing, blowing, and naturally cooling to obtain the slow-release microcapsule film.

Further, in the step (1), when the material a is prepared, the temperature of the refrigerator is reduced to-45 ℃, and the freezing time is 4-5 hours; controlling the heating rate to be 1 ℃/h, heating to 30 ℃, and keeping the temperature for 24 h; and the volume ratio of hydrogen to argon in the preparation of the material b is 1: 9; the heating rate is 10 ℃/min, and the reaction time is 2-3 h; when the cellulose gel is prepared, the reaction time is 24 hours after the temperature is raised to 90 ℃; the reaction time is 30min at constant temperature.

Further, in the step (2), the vacuum degree of the vacuum drying oven was 1Pa, and the drying time was 24 hours.

Further, in the step (3), the soaking time is 10-15 min, and the mass ratio of the modified cellulose aerogel, the copper sulfate solution, the sodium hydroxide solution and the hydrazine hydrate is 1: 6: 6: 6.

further, in the step (4), the mass ratio of the 2-methylthio-4, 6-diisopropylamino-sym-triazine solvent to the methyl alcohol solvent to the curing agent vinyl triamine is 1: 29: 1.3.

further, in the step (6), the mass ratio of urea, formaldehyde solution, melamine, glycolic acid and emulsifier sodium alkyl benzene sulfonate is 1: 3: 1.2: 1: 0.1, the mass ratio of the modified core material to the formaldehyde solution is 1: 4; the mass ratio of the mixed solution II to the wall material solution is 1: 3.

further, the sustained-release microcapsule film prepared by the preparation method of the sustained-release microcapsule film comprises the following raw materials in parts by weight: 30-50 parts of modified core material, 100-200 parts of curing liquid, 90-150 parts of melamine-urea-glycolic acid prepolymer and 300-500 parts of polyethylene; the modified core material is prepared by processing waste cotton fibers; the curing liquid is prepared by dissolving 2-methylthio-4, 6-diisopropylamino sym-triazine in a methanol solvent and adding a curing agent of vinyl triamine.

Compared with the prior art, the invention has the following beneficial effects:

the method comprises the steps of preparing cellulose aerogel by using waste cotton fibers as a raw material and adopting a freeze drying technology, carrying out hydrophobic modification on the cellulose aerogel to prepare pre-modified cellulose aerogel, and depositing cuprous oxide on the pre-modified cellulose aerogel by adopting a chemical in-situ deposition method to prepare modified cellulose aerogel; waste cotton fibers are used as raw materials to realize waste recycling, the quality of the microcapsules is lighter and thinner due to the formation of the aerogel, and meanwhile, the prepared microcapsules can be guaranteed to have a large number of porous net-shaped structures, so that the integrity of the microcapsules under the stress action is improved while the outline of the microcapsules is formed; hydrophobic modification enables the microcapsules to show water repellency, the microcapsules cannot be directly dissolved or show water absorption in the presence of water, a dry environment is provided for the medicine in the microcapsules, the slow release effect of the microcapsules is promoted, meanwhile, the water resistance of cellulose is improved, and the cellulose is prevented from being rapidly rotten in a humid environment; the hydrophobic modifier methyl trichlorosilane and hydroxyl on the surface of cellulose form carbon-oxygen-silicon covalent bonding and act with a porous network structure to form a plurality of grids, and octahedral cuprous oxide nanoparticles are uniformly embedded on the formed grids, so that the microcapsules are endowed with photocatalytic performance while the nanoparticles are effectively prevented from agglomerating, the degradation rate of the microcapsules is improved, nutrient elements are supplemented for microorganisms in soil, and the fertility of the soil is enhanced.

Dissolving 2-methylthio-4, 6-bis-isopropylamino sym-triazine in a methanol solvent, adding a curing agent vinyl triamine to prepare a curing solution, placing modified cellulose aerogel in a mold, pouring the curing solution into the mold, sealing the mold, pressurizing the interior of the mold, drying a product in the mold to prepare a pretreated core material, and crushing the pretreated core material by using ball milling operation to obtain the modified core material; coating a modified core material by taking a melamine-urea-glycolic acid prepolymer as a wall material to obtain a modified microcapsule, adding the modified microcapsule into molten polyethylene, uniformly mixing, blowing, and cooling to obtain a slow-release microcapsule film; under the action of pressure, the curing liquid is pressed into the aerogel, and the 2-methylthio-4, 6-diisopropylamino sym-triazine has better compatibility with the aerogel due to the hydrophobicity of the aerogel; the modified core material is coated by using the melamine-urea-glycolic acid prepolymer as a wall material, glycolic acid has a chelation effect on copper ions, the binding force between the wall material and the core material is increased, the wall material chelates the copper ions inside, and the transparent wall material enables light rays to be irradiated onto the copper ions through the wall material, so that the photocatalytic property of the film is improved; the modified microcapsules are added into the molten polyethylene, when the film blowing operation is carried out, the shear stress of the film blowing machine on the microcapsules is dispersed in a porous net shape in the microcapsules, the integrity of the microcapsules is ensured, the nanometer modified microcapsules are embedded on the film, when the modified microcapsules are used for weeding before the emergence, under the irradiation of sunlight, copper ions in the microcapsules start to play a photocatalysis effect, the wall materials are slowly damaged, the medicine is released outwards, and weeds in soil are killed; the cellulose can quickly degrade the microcapsule film with the slow release effect at the later stage, and the microcapsule film is nontoxic and has no residue.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

To more clearly illustrate the method of the present invention, the following examples are given, and the method for testing the sustained-release microcapsule film prepared in the following examples is as follows:

hydrophobicity: the sustained-release microcapsule films prepared in examples 1, 2 and 1 were subjected to hydrophobicity tests, and the static contact angles of the surfaces of the sustained-release microcapsule films of the components of examples 1, 2 and 1 were measured using a contact angle tester model OCA20 with the size of water droplets being 8 μ L, and the larger the static contact angle, the better the hydrophobicity.

Degradation performance: the sustained-release microcapsule films prepared in examples 1, 2 and 2 were placed in a soil environment with a humidity of 50% and a temperature of 25 ℃, and the degradation cycles of the sustained-release microcapsule films prepared in examples 1, 2 and 2 were recorded under simulated sunlight conditions, with the shorter the cycle, the better the degradation effect of the sustained-release microcapsule films.

Example 1

A microcapsule film with sustained release effect mainly comprises the following components in parts by weight: 50 parts of modified core material, 200 parts of curing liquid, 150 parts of melamine-urea-glycolic acid prepolymer and 500 parts of polyethylene.

A preparation method of a microcapsule film with sustained release effect mainly comprises the following preparation steps:

(1) crushing clean waste cotton fibers into small sections of 0.2mm to obtain crushed cellulose, dispersing the crushed cellulose in 7% sodium hydroxide solution to prepare 20mg/ml dispersion liquid I, performing ultrasonic dispersion for 10min at the frequency of 50Hz, diluting the dispersion liquid I into 10mg/ml dispersion liquid II by using 7% sodium hydroxide solution, pouring the dispersion liquid II into a freeze-drying mold, adjusting a freeze-drying machine into a freezing mode, cooling and freezing, adjusting the freeze-drying machine into a drying mode, vacuumizing to set the vacuum degree to 1Pa, heating the mold, preserving heat for a period of time, and naturally cooling to obtain a material a; adding the material a into a tubular heating furnace, raising the temperature to 500 ℃ in a mixed gas atmosphere consisting of hydrogen and argon, carrying out heat preservation reaction, and naturally cooling to obtain a material b; soaking the material b in a tetrahydrofuran solution with the concentration of 15%, then placing the material b into a dryer, sealing the dryer, placing the dryer into an air-blowing drying oven, heating to 90 ℃, starting reaction, raising the temperature of the air-blowing drying oven to 200 ℃ after the reaction is finished, carrying out constant-temperature reaction, naturally cooling, and washing the product in deionized water until the washing liquid is neutral to obtain the cellulose aerogel; wherein, when preparing the material a, the refrigerator is cooled to-45 ℃ for 5 h; controlling the heating rate to be 1 ℃/h, heating to 30 ℃, and keeping the temperature for 24 h; and the volume ratio of hydrogen to argon in the preparation of the material b is 1: 9; the heating rate is 10 ℃/min, and the reaction time is 3 h; when the cellulose gel is prepared, the reaction time is 24 hours after the temperature is raised to 90 ℃; the constant temperature reaction time is 30 min;

(2) placing cellulose aerogel in a closed dryer, simultaneously placing an open beaker containing methyltrichlorosilane with the mass 5 times that of the cellulose aerogel in the dryer, sealing the dryer at normal temperature for 24 hours to perform silanization reaction, and after the reaction is finished, placing the silanized cellulose aerogel in a vacuum drying oven at normal temperature to remove unreacted silane to prepare the pre-modified cellulose aerogel; wherein the vacuum degree of the vacuum drying oven is 1Pa, and the drying time is 24 h;

(3) soaking the pre-modified cellulose aerogel in a copper sulfate solution with the mass fraction of 2%, then soaking the pre-modified cellulose aerogel soaked in a copper persulfate solution in a sodium hydroxide solution with the pH value of 12, transferring the pre-modified cellulose aerogel soaked in the sodium hydroxide solution to 1% hydrazine hydrate, soaking in a normal temperature environment, and finally washing a product with deionized water until a washing solution is neutral to prepare the modified cellulose aerogel; wherein the soaking time is 15min, and the mass ratio of the modified cellulose aerogel to the copper sulfate solution to the sodium hydroxide solution to the hydrazine hydrate is 1: 6: 6: 6;

(4) dissolving 2-methylthio-4, 6-diisopropylamino sym-triazine in a methanol solvent, adding a curing agent vinyl triamine, and uniformly mixing to obtain a curing liquid; wherein the mass ratio of the 2-methylthio-4, 6-diisopropylamino sym-triazine solvent to the methanol solvent to the curing agent vinyl triamine is 1: 29: 1.3

(5) Placing the modified cellulose gel in a mold, pouring curing liquid with the amount of 5 times that of the modified cellulose gel, sealing the mold, and carrying out vacuum drying on the interior of the mold, wherein the vacuum degree is-0.1 MPa, the drying temperature is 80 ℃, and the drying time is 6 hours, so as to obtain a pretreated core material; performing ball milling operation on the pretreated core material, taking deionized water as a grinding-aid solvent, wherein the ball-material ratio is 5: 3, the mass ratio of the pretreated core material to the deionized water is 3: 1, the grain diameter of the pretreated core material after ball milling is 1000nm, and a modified core material is prepared;

(6) dispersing urea into a 30 mass percent formaldehyde solution, simultaneously adding melamine, glycolic acid and an emulsifier sodium alkyl benzene sulfonate, adjusting the pH to 8.3, uniformly stirring to obtain a mixed solution I, placing the mixed solution I in a water bath with the constant temperature of 60 ℃, and stirring at the speed of 200r/min for 40min to obtain a wall material solution; dispersing the modified core material into a 30% formaldehyde solution, uniformly stirring to obtain a mixed solution II, placing the mixed solution II in a 40 ℃ water bath, stirring at the speed of 200r/min, simultaneously dropwise adding a wall material solution at the dropping speed of 3 drops/s, reacting for 30min, and then carrying out hot air drying on a reaction system at the drying temperature of 70 ℃ for 5h to obtain modified microcapsules; wherein the mass ratio of urea to formaldehyde solution to melamine to glycolic acid to the emulsifier sodium alkyl benzene sulfonate is 1: 3: 1.2: 1: 0.1, the mass ratio of the modified core material to the formaldehyde solution is 1: 4; the mass ratio of the mixed solution II to the wall material solution is 1: 3;

(7) dispersing the modified microcapsule in molten polyethylene 10 times the weight of the modified microcapsule, adding curing agent vinyl triamine 0.03 time the weight of the molten polyethylene, mixing, blowing, and naturally cooling to obtain the slow-release microcapsule film.

Example 2

A microcapsule film with sustained release effect mainly comprises the following components in parts by weight: 30 parts of modified core material, 100 parts of curing liquid, 90 parts of melamine-urea-glycolic acid prepolymer and 300 parts of polyethylene.

A preparation method of a microcapsule film with sustained release effect mainly comprises the following preparation steps:

(1) crushing clean waste cotton fibers into small sections of 0.2mm to obtain crushed cellulose, dispersing the crushed cellulose in 7% sodium hydroxide solution to prepare 20mg/ml dispersion liquid I, performing ultrasonic dispersion for 10min at the frequency of 50Hz, diluting the dispersion liquid I into 10mg/ml dispersion liquid II by using 7% sodium hydroxide solution, pouring the dispersion liquid II into a freeze-drying mold, adjusting a freeze-drying machine into a freezing mode, cooling and freezing, adjusting the freeze-drying machine into a drying mode, vacuumizing to set the vacuum degree to 1Pa, heating the mold, preserving heat for a period of time, and naturally cooling to obtain a material a; adding the material a into a tubular heating furnace, raising the temperature to 500 ℃ in a mixed gas atmosphere consisting of hydrogen and argon, carrying out heat preservation reaction, and naturally cooling to obtain a material b; soaking the material b in a tetrahydrofuran solution with the concentration of 15%, then placing the material b into a dryer, sealing the dryer, placing the dryer into an air-blowing drying oven, heating to 90 ℃, starting reaction, raising the temperature of the air-blowing drying oven to 200 ℃ after the reaction is finished, carrying out constant-temperature reaction, naturally cooling, and washing the product in deionized water until the washing liquid is neutral to obtain the cellulose aerogel; wherein, when preparing the material a, the refrigerator is cooled to-45 ℃ for 4 h; controlling the heating rate to be 1 ℃/h, heating to 30 ℃, and keeping the temperature for 24 h; and the volume ratio of hydrogen to argon in the preparation of the material b is 1: 9; the heating rate is 10 ℃/min, and the reaction time is 2 h; when the cellulose gel is prepared, the reaction time is 24 hours after the temperature is raised to 90 ℃; the constant temperature reaction time is 30 min;

(2) placing cellulose aerogel in a closed dryer, simultaneously placing an open beaker containing methyltrichlorosilane with the mass 5 times that of the cellulose aerogel in the dryer, sealing the dryer at normal temperature for 24 hours to perform silanization reaction, and after the reaction is finished, placing the silanized cellulose aerogel in a vacuum drying oven at normal temperature to remove unreacted silane to prepare the pre-modified cellulose aerogel; wherein the vacuum degree of the vacuum drying oven is 1Pa, and the drying time is 24 h;

(3) soaking the pre-modified cellulose aerogel in a copper sulfate solution with the mass fraction of 2%, then soaking the pre-modified cellulose aerogel soaked in a copper persulfate solution in a sodium hydroxide solution with the pH value of 12, transferring the pre-modified cellulose aerogel soaked in the sodium hydroxide solution to 1% hydrazine hydrate, soaking in a normal temperature environment, and finally washing a product with deionized water until a washing solution is neutral to prepare the modified cellulose aerogel; wherein the soaking time is 10min, and the mass ratio of the modified cellulose aerogel to the copper sulfate solution to the sodium hydroxide solution to the hydrazine hydrate is 1: 6: 6: 6;

(4) dissolving 2-methylthio-4, 6-diisopropylamino sym-triazine in a methanol solvent, adding a curing agent vinyl triamine, and uniformly mixing to obtain a curing liquid; wherein the mass ratio of the 2-methylthio-4, 6-diisopropylamino sym-triazine solvent to the methanol solvent to the curing agent vinyl triamine is 1: 29: 1.3

(5) Placing the modified cellulose gel in a mold, pouring curing liquid with the amount of 5 times that of the modified cellulose gel, sealing the mold, and carrying out vacuum drying on the interior of the mold, wherein the vacuum degree is-0.1 MPa, the drying temperature is 80 ℃, and the drying time is 5 hours, so as to obtain a pretreated core material; performing ball milling operation on the pretreated core material, taking deionized water as a grinding-aid solvent, wherein the ball-material ratio is 5: 3, the mass ratio of the pretreated core material to the deionized water is 3: 1, the grain diameter of the pretreated core material after ball milling is 900nm, and a modified core material is prepared;

(6) dispersing urea into 30 mass percent of formaldehyde solution, simultaneously adding melamine, glycolic acid and emulsifier sodium alkyl benzene sulfonate, adjusting the pH to 8.3, uniformly stirring to obtain a mixed solution I, placing the mixed solution I in a water bath with the constant temperature of 60 ℃, and stirring at the speed of 200r/min for 30min to obtain a wall material solution; dispersing the modified core material into a 30% formaldehyde solution, uniformly stirring to obtain a mixed solution II, placing the mixed solution II in a 40 ℃ water bath, stirring at the speed of 200r/min, simultaneously dropwise adding a wall material solution at the dropping speed of 3 drops/s, reacting for 20min, and then carrying out hot air drying on a reaction system at the drying temperature of 60 ℃ for 3-5 h to obtain modified microcapsules; wherein the mass ratio of urea to formaldehyde solution to melamine to glycolic acid to the emulsifier sodium alkyl benzene sulfonate is 1: 3: 1.2: 1: 0.1, the mass ratio of the modified core material to the formaldehyde solution is 1: 4; the mass ratio of the mixed solution II to the wall material solution is 1: 3;

(7) dispersing the modified microcapsule in molten polyethylene 10 times the weight of the modified microcapsule, adding curing agent vinyl triamine 0.03 time the weight of the molten polyethylene, mixing, blowing, and naturally cooling to obtain the slow-release microcapsule film.

Comparative example 1

The formulation of comparative example 1 was the same as example 1. The preparation method of the sustained-release microcapsule film is different from that of the example 1 only in that the cellulose aerogel is not subjected to hydrophobic modification, and the rest of the preparation steps are the same as those of the example 1.

Comparative example 2

Comparative example 2 was formulated as in example 1. The preparation method of the glass brick of the sustained-release microcapsule film is different from that of example 1 only in that the preparation of step (3) is not performed, and the rest of the preparation steps are the same as those of example 1.

Effect example 1

The following table 1 shows the results of the water resistance analysis of the sustained-release microcapsule films using the components of examples 1 and 2 of the present invention and comparative example 1.

TABLE 1

The static contact angle is an index for measuring hydrophobicity, the larger the static contact angle is, the better the hydrophobic property is, and as can be seen from the table above, the sustained-release microcapsule film prepared by the component in example 1 shows excellent waterproof property, which indicates that the microcapsule can not be directly dissolved or shows water absorption in the presence of water, so as to provide a dry environment for the drug in the microcapsule, promote the sustained-release effect of the microcapsule, increase the water resistance of cellulose, and prevent the cellulose from being rapidly rotten in a humid environment.

Effect example 2

The following table 2 shows the results of the degradation performance analysis of the sustained-release microcapsule films using the components of examples 1 and 2 of the present invention and comparative example 2.

TABLE 2

	Example 1	Example 2	Comparative example 2
				Degradation period	7 days	7 days	9 days

As can be seen from the above table, both examples 1 and 2 show excellent degradation performance, which indicates that the modifier methyltrichlorosilane and hydroxyl on the surface of cellulose form carbon-oxygen-silicon covalent bond, and interact with the porous network structure to form a plurality of grids, and the octahedral cuprous oxide nanoparticles are uniformly embedded on the formed grids, so that the nanoparticles are effectively prevented from agglomerating, and at the same time, the photocatalytic performance of the microcapsules is endowed, the degradation rate of the microcapsules is increased, and nutrient elements are supplemented for the microorganisms in the soil, so that the fertility of the soil is enhanced.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.