CN113563517A

CN113563517A - Garlic residue-based liquid mulching film and preparation method thereof

Info

Publication number: CN113563517A
Application number: CN202110952518.5A
Authority: CN
Inventors: 李文卓; 耿浩浩; 王丹阳
Original assignee: Nanjing Forestry University
Current assignee: Nanjing Forestry University
Priority date: 2021-08-19
Filing date: 2021-08-19
Publication date: 2021-10-29
Anticipated expiration: 2041-08-19
Also published as: CN113563517B; CN115215966B; CN115181301A; CN115215966A; CN115181301B

Abstract

The invention provides a garlic residue-based liquid mulching film and a preparation method thereof, the preparation of the mulching film adopts a mixture of garlic residue slurry, pregelatinized starch and acrylic acid monomer as main raw materials, and the reaction process relates to a pre-oxidation process, a pre-emulsification process and an emulsion free radical polymerization process under the action of an initiator; the emulsion obtained after the reaction is not easy to separate and has stability, proper viscosity and sprayability; compared with bare soil without mulching film, the garlic residue-based mulching film can improve the water content and soil temperature in soil and can also improve the yield of the pakchoi. The garlic residue-based liquid mulching film can resist the invasion of the plantula rapae moths to the plantula rapae. The invention fully utilizes the waste crop resource of the garlic residue, has low cost, few production links and easy operation, and is suitable for popularization and application.

Description

Garlic residue-based liquid mulching film and preparation method thereof

The technical field is as follows:

the invention provides a garlic residue-based liquid mulching film and a preparation method thereof, belonging to the technical field of agricultural mulching films.

Background art:

china is a main country for producing garlic in the world, the planting history of garlic in China dates back two thousand years, and the garlic cultivation in China has long history, large cultivation area and high yield. Compared with other crops, the garlic is rich in alliin which exists in a stable and odorless form, but allinase in the garlic is activated after the garlic is sliced or crushed, and the allicin forms colorless oily allicin under the catalysis of the allinase. The allicin has various biological activities, such as cardiovascular disease prevention and treatment, tumor resistance, pathogenic microorganism resistance and the like, and can play a role in disease prevention and health care after long-term consumption. The garlic residue is residue left after extracting allicin oil from garlic by a distillation method and the like, the garlic residue left after extracting allicin accounts for about 99.5 percent of the total weight of the garlic, and the garlic residue is rarely utilized at present and is mostly discarded. In recent years, the demand for allicin oil at home and abroad is continuously rising, a large amount of garlic residue waste is correspondingly generated, the natural resources of garlic crops are greatly wasted, and the garlic residues have strong pungent odor, so that the garlic residues are further rotten and seriously pollute the surrounding environment, and therefore, a new product capable of effectively utilizing the garlic residues is urgently needed to be developed.

The plastic film mulching technology has proved that the plastic film mulching technology can play a role in heat preservation and moisture preservation of the soil by blocking the loss rate of water and heat in the agricultural soil to the atmosphere, thereby further generating the yield increasing effect of crops. At present, the traditional agricultural mulching film is mainly a single plastic mulching film made of polyethylene or polyvinyl chloride. The traditional plastic mulching film is a formed mulching film, namely a film is manufactured in advance through special equipment, then the film is packaged into a roll and transported to the field, and the whole film is laid on the soil surface of the field. The traditional plastic mulching film has the following defects: (1) the fertilizer is not biodegradable, and can damage the ecological environment of agricultural soil; (2) the function is single, if the plant diseases and insect pests occur in farmland soil, holes need to be broken on the film (sometimes the whole film needs to be lifted), pesticides and the like which can inhibit the growth of harmful germs or pests in the soil are applied from the broken holes, but the water retention and heat preservation effects of the broken film on the soil are seriously weakened. Therefore, the development of the mulching film product with certain disease and insect resistant function is significant.

At present, a sprayable liquid mulching film is developed at home and abroad, the liquid mulching film is liquid before use, is uniformly sprayed on the ground surface when used, and forms a film on the soil surface after air drying, so that the film has the functions of heat preservation and moisture preservation. Compared with the traditional plastic mulching film, the production process of the liquid mulching film has fewer links, the surface film forming process is simple, the use cost of the mulching film is greatly saved, and the raw materials used by the liquid mulching film mainly come from humic acid, lignin, collagen and other degradable natural high polymer materials, so that the liquid mulching film has little influence on the ecological environment and can effectively solve the problem of soil pollution caused by the traditional plastic mulching film. Liquid mulching films have now become a replacement for traditional plastic mulching films in many fields, such as agriculture and horticulture. At present, no report is found on products which are made of garlic residues into liquid mulching films.

The invention content is as follows:

the invention aims to provide a method for preparing a liquid mulching film by using garlic residues as raw materials, which is simple, has easily obtained raw materials, low cost and easy market popularization and application.

The invention also provides a garlic residue-based liquid mulching film which has the effects of moisturizing and preserving soil and also has the effect of resisting the damage of cabbage moths to pakchoi.

The specific technical scheme of the invention is as follows:

the preparation method of the garlic residue-based liquid mulching film comprises the following steps:

(1) crushing the garlic residues into garlic residue slurry by using a crusher, and filtering the obtained garlic residue slurry by using a screen to ensure that the garlic residue particle size in the filtered garlic residue slurry is less than 10 meshes;

(2) mixing pregelatinized starch and water at 25-35 deg.C to obtain starch slurry, wherein the mass ratio of pregelatinized starch to water is (0.15-0.21): 1;

(3) mixing the garlic residue slurry obtained in the step (1) with the starch slurry obtained in the step (2), and stirring for 1-5h at 25-35 ℃ at the stirring speed of 200-3000r/min to obtain the garlic residue-starch slurry, wherein the mass ratio of the garlic residue slurry to the starch slurry is (0.09-0.6): 1;

(4) adding the garlic residue-starch slurry obtained in the step (3) into a reaction vessel provided with a stirrer, a thermometer and a condenser pipe, then adding an oxidant aqueous solution into the reaction vessel while stirring at the temperature of 80-90 ℃, wherein the stirring speed is 200-1500r/min, and the stirring time is 1-3h, and then obtaining pre-oxidized garlic residue-starch slurry, wherein the mass ratio of the garlic residue-starch slurry obtained in the step (3) to the oxidant aqueous solution is (3.5-5.8): 1;

(5) mixing the pre-oxidized garlic residue-starch slurry obtained in the step (4) with an acrylic acid monomer mixture, an emulsifier and water, and pre-emulsifying the obtained mixture for 30-120min at 45-60 ℃ and a stirring speed of 200-5000r/min to obtain a pre-emulsified mixture, wherein the mass ratio of the pre-oxidized garlic residue-starch slurry obtained in the step (4) to the acrylic acid monomer mixture to the emulsifier to the water is (14-21): (5-11): 1: (13-27);

(6) raising the temperature of the pre-emulsified mixture obtained in the step (5) to 75-90 ℃, and dropwise adding an initiator aqueous solution into the pre-emulsified mixture at a dropping speed of 0.05-0.3mL/min while stirring at a constant temperature, wherein the mass ratio of the pre-emulsified mixture obtained in the step (5) to the initiator aqueous solution is (4.8-5.6): 1; after the initiator is added dropwise, the reaction is continued for 2-8h under the conditions of 75-90 ℃ and the stirring speed of 250-500r/min, then the reaction system is cooled to room temperature, and the pH value of the system is adjusted to 7.0-9.0 by ammonia water, thus obtaining the emulsion which can be used as the garlic residue-based liquid mulching film.

The invention is further designed in that:

and (3) the oxidant aqueous solution in the step (4) is a potassium persulfate or ammonium persulfate aqueous solution, wherein the mass percentage concentration of the potassium persulfate or the ammonium persulfate is 6-12%.

The acrylic acid monomer mixture in the step (5) comprises butyl acrylate, methyl methacrylate and acrylic acid, wherein the mass ratio of the butyl acrylate to the methyl methacrylate to the acrylic acid is (5.5-6.5): (2.5-3.5): 1.

the emulsifier in the step (5) is a mixture of a reactive emulsifier and octylphenol polyoxyethylene ether (10), wherein the mass ratio of the reactive emulsifier to the octylphenol polyoxyethylene ether is 1: (2.5-3.5), and the type of the reactive emulsifier is LRS-10.

The mass percentage concentration of the ammonia water in the step (6) is 25%.

The initiator aqueous solution in the step (6) is potassium persulfate or ammonium persulfate aqueous solution, wherein the mass percentage concentration of the potassium persulfate or the ammonium persulfate is 2.2-3.1%.

The water used in steps (2) - (6) is deionized water.

The invention also provides the liquid mulching film prepared by the preparation method and taking the garlic residues as the raw material, and the application of the liquid mulching film in the aspect of agricultural mulching films.

Compared with the prior art, the invention has the following advantages:

the invention utilizes the agricultural waste garlic residues to prepare the liquid mulching film, fully recycles the garlic residue resources, and realizes the effect of changing the garlic residues into valuables. Different from the traditional petroleum-based plastic mulching film (such as a polyvinyl mulching film), the garlic residue-based liquid mulching film prepared by the invention is an emulsion-shaped liquid before use, has sprayability, can be sprayed on the surface of soil to form a liquid film layer, and can be automatically dried in the air, thereby playing a role in preventing the outward loss of moisture and heat in the soil. Effect example test results show that the garlic residue-based liquid mulching film prepared by the invention has water retention and heat preservation effects, and meanwhile, the liquid mulching film has the effects of increasing the yield of pakchoi and reducing the damage of the growth of pakchoi by pakchoi moths.

The working principle of the invention is analyzed as follows:

1. the step (1) of the invention is to crush the garlic residue into garlic residue pulp by a crusher and filter the obtained garlic residue pulp by a screen mesh, so that the particle size of the garlic residue in the filtered garlic residue pulp is smaller than 10 meshes. The garlic residue particles are reduced, so that the emulsion prepared by the invention can be smoothly sprayed, and the phenomenon that large particles in the emulsion block a nozzle of a spray gun can not occur.

2. The steps (2) and (3) of the invention are the process for preparing the garlic residue-starch slurry, and pre-gelatinized starch is adopted in the preparation process. The pregelatinized starch is prepared by swelling starch granules in water at a proper temperature (generally 60-80 deg.C), splitting to form uniform pasty solution, and dehydrating and drying freshly prepared gelatinized starch slurry. The pregelatinized starch is easily dispersed in cold water, and can be made into pasty colloid. The starch belongs to polyglucose molecules, the molecular structure contains a large amount of hydrophilic hydroxyl, and the garlic residues are rich in cellulose and other hydrophilic molecules, so that the starch molecules and the garlic residues can be combined together through the interaction of hydrogen bonds and the like. The method ensures that the garlic residue particles in the garlic residue slurry can be suspended in the colloid formed by the pregelatinized starch and are not easy to settle, so that the garlic residue particles are more uniformly distributed in the garlic residue-starch slurry, the mulching film emulsion prepared by the method is more uniform, and the sprayability of the emulsion is not easily influenced by the coagulation and layering phenomena among the garlic residue particles.

3. The step (4) of the invention is a process for preparing preoxidized garlic residue-starch slurry, potassium persulfate or ammonium persulfate is used as an oxidant, a large amount of hydroxyl exists in the garlic residue and the starch, and the oxidant can oxidize part of the hydroxyl in the garlic residue and the starch into carboxyl, so that the association effect generated by hydrogen bonds between system molecules can be reduced to a certain extent, the viscosity of the system is favorably reduced, and the prepared mulching film emulsion has more proper fluidity and is favorable for the emulsion to be suitable for subsequent spraying operation.

4. Step (5) of the present invention is to mix the pre-oxidized garlic residue-starch slurry obtained in step (4) with an acrylic acid monomer mixture, an emulsifier and water to obtain a pre-emulsified mixture, which is prepared for the next emulsion polymerization reaction. Under the conditions of proper temperature and stirring, a certain amount of emulsifier can enable the pre-oxidized garlic residue-starch slurry and acrylic monomer mixture to form an emulsion system consisting of oil-in-water type homogeneous droplets, the space formed by each micro droplet is a micro reactor, and garlic residue, starch and acrylic monomer molecules are fully contacted in the micro reactor, so that conditions are provided for initiating efficient emulsion free radical polymerization reaction among the garlic residue-starch slurry and the acrylic monomer molecules in the next step.

5. Step (6) of the invention is to drop initiator into the pre-emulsified mixture obtained in step 5, under certain conditions, the initiator can trigger free radical polymerization reaction, so that molecules such as cellulose, protein and the like in garlic residue and starch molecules can be grafted with butyl acrylate, methyl methacrylate and acrylic acid to form polymer chains, the polymer chains can exist in emulsion in the form of liquid drops, when the prepared emulsion is sprayed on the soil surface, the crosslinking degree among the polymer chains is continuously increased along with the continuous increase of moisture in the emulsion, and finally a compact film is formed to cover the soil surface, and the film can play a role in preventing the moisture and heat in the soil from being dissipated outwards.

6. The garlic residue basement membrane prepared by the invention is uniformly distributed with garlic residues, the garlic residues contain allicin, the allicin is an organic sulfur compound, the chemical name is diallyl thiosulfinate, and the chemical formula is C₆H₁₀OS₂Allicin is volatile and emits a strong garlic odor. Allicin has been proved to have strong antibacterial effect and good expelling effect on small insects such as mould, virus, protozoa, pinworm, aphid, etc. Allicin is also used in agriculture as a natural biological agent for killing pests and germs that can harm crops. The allicin in the garlic residue-based mulching film prepared by the invention can be emitted to play a role in expelling insects, and the allicin also needs to volatilize outwards through a compact three-dimensional network formed by winding polymer chains in the mulching film, so that the emitting rate of the allicin is reduced, the slow release effect on the allicin is played, and the long-acting insect prevention effect of the mulching film is favorably exerted.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.

FIG. 1 is a process flow chart of the invention for preparing garlic residue-based liquid mulching film.

Detailed Description

The above and further features and advantages of the present invention are explained in more detail below with reference to examples. The chemical raw materials used in the following examples are all commercially available, chemically pure reagents;

butyl acrylate, methyl methacrylate, and acrylic acid, all 99% pure and 25% aqueous ammonia, were purchased from Daloco Chemicals, Inc. (Tianjin, China).

A reaction type emulsifier (model: LRS-10) having a purity of 99% and octylphenol polyoxyethylene ether (10) (OP-10) having a purity of 99% were purchased from chemical reagents, Inc., Jiangsu, China.

Potassium persulfate and ammonium persulfate at 99.5% purity were purchased from Ringshot Chemicals, Inc. (Shanghai, China).

Pregelatinized starch, food grade, was purchased from Zhejiang Hongyi Biotechnology Inc. (Jinhua, Zhejiang).

Example 1

(2) mixing pregelatinized starch and water at 28 ℃ to form a starch slurry, wherein the mass ratio of the pregelatinized starch to the water is 0.15: 1;

(3) mixing the garlic residue slurry obtained in the step (1) with the starch slurry obtained in the step (2), and stirring for 1h at 35 ℃ at a stirring speed of 200r/min to obtain a garlic residue-starch slurry, wherein the mass ratio of the garlic residue slurry to the starch slurry is 0.09: 1;

(4) adding the garlic residue-starch slurry obtained in the step (3) into a three-neck flask provided with a stirrer, a thermometer and a condenser, adding an oxidant aqueous solution into the flask while stirring at 80 ℃, wherein the stirring speed is 1500r/min, and the stirring time is 1h, and then obtaining a pre-oxidized garlic residue-starch slurry, wherein the mass ratio of the garlic residue-starch slurry obtained in the step (3) to the oxidant aqueous solution is 3.5: 1;

(5) mixing the pre-oxidized garlic residue-starch slurry obtained in the step (4) with an acrylic acid monomer mixture, an emulsifier and water, and pre-emulsifying the obtained mixture at 45 ℃ and a stirring speed of 200r/min for 60min to obtain a pre-emulsified mixture, wherein the mass ratio of the pre-oxidized garlic residue-starch slurry obtained in the step (4) to the acrylic acid monomer mixture to the emulsifier to the water is 14: 5: 1: 13;

(6) raising the temperature of the pre-emulsified mixture obtained in the step (5) to 75 ℃, and dropwise adding an initiator aqueous solution into the pre-emulsified mixture at a dropping speed of 0.05mL/min while stirring, wherein the mass ratio of the pre-emulsified mixture obtained in the step (5) to the initiator aqueous solution is 4.8: 1; after the initiator is added dropwise, the reaction is continued for 2h at 75 ℃ and at a stirring speed of 250r/min, then the reaction system is cooled to room temperature, and the pH value of the system is adjusted to 7.0 by ammonia water, thus obtaining the emulsion which can be used as the garlic residue-based liquid mulching film.

Wherein the oxidant aqueous solution in the step (4) is ammonium persulfate aqueous solution, and the mass percentage concentration of the ammonium persulfate is 6%. The acrylic acid monomer mixture in the step (5) comprises butyl acrylate, methyl methacrylate and acrylic acid, wherein the mass ratio of the butyl acrylate to the methyl methacrylate to the acrylic acid is 5.5:3.5: 1. The emulsifier in the step (5) is a mixture of a reactive emulsifier and octylphenol polyoxyethylene ether (10), wherein the mass ratio of the reactive emulsifier to the octylphenol polyoxyethylene ether is 1:2.5, and the type of the reactive emulsifier is LRS-10. The mass percentage concentration of the ammonia water in the step (6) is 25%. The initiator aqueous solution in the step (6) is an ammonium persulfate aqueous solution, wherein the mass percentage concentration of ammonium persulfate is 2.2%. The water used in steps (2) - (6) is deionized water.

The garlic residue-based liquid mulching film of the embodiment 1 can be obtained through the steps (1) to (6), the appearance of the garlic residue-based liquid mulching film is uniform and stable emulsion, and no layering phenomenon occurs after standing for 30 days.

Example 2

(2) mixing pregelatinized starch and water at 32 ℃ to form a starch slurry, wherein the mass ratio of the pregelatinized starch to the water is 0.2: 1;

(3) mixing the garlic residue slurry obtained in the step (1) with the starch slurry obtained in the step (2), and stirring for 2h at 28 ℃ and the stirring speed of 1000r/min to obtain the garlic residue-starch slurry, wherein the mass ratio of the garlic residue slurry to the starch slurry is 0.5: 1;

(4) adding the garlic residue-starch slurry obtained in the step (3) into a three-neck flask provided with a stirrer, a thermometer and a condenser, adding an oxidant aqueous solution into the flask while stirring at 88 ℃, wherein the stirring speed is 1000r/min, and the stirring time is 3h, and then obtaining a pre-oxidized garlic residue-starch slurry, wherein the mass ratio of the garlic residue-starch slurry obtained in the step (3) to the oxidant aqueous solution is 5.4: 1;

(5) mixing the pre-oxidized garlic residue-starch slurry obtained in the step (4) with an acrylic acid monomer mixture, an emulsifier and water, and pre-emulsifying the obtained mixture for 90min at 55 ℃ and at a stirring speed of 3000r/min to obtain a pre-emulsified mixture, wherein the mass ratio of the pre-oxidized garlic residue-starch slurry obtained in the step (4) to the acrylic acid monomer mixture to the emulsifier to the water is 19: 10: 1: 17;

(6) raising the temperature of the pre-emulsified mixture obtained in the step (5) to 85 ℃, and dropwise adding an initiator aqueous solution into the pre-emulsified mixture at a dropping speed of 0.22mL/min while stirring, wherein the mass ratio of the pre-emulsified mixture obtained in the step (5) to the initiator aqueous solution is 5.0: 1; after the initiator is added dropwise, the reaction is continued for 4 hours at 85 ℃ and at a stirring speed of 420r/min, then the reaction system is cooled to room temperature, and the pH value of the system is adjusted to 8.0 by ammonia water, thus obtaining the emulsion which can be used as the garlic residue-based liquid mulching film.

Wherein the oxidant aqueous solution in the step (4) is a potassium persulfate aqueous solution, and the mass percentage concentration of the potassium persulfate is 8%. The acrylic acid monomer mixture in the step (5) comprises butyl acrylate, methyl methacrylate and acrylic acid, wherein the mass ratio of the butyl acrylate to the methyl methacrylate to the acrylic acid is 5.8:3.3: 1. The emulsifier in the step (5) is a mixture of a reactive emulsifier and octylphenol polyoxyethylene ether (10), wherein the mass ratio of the reactive emulsifier to the octylphenol polyoxyethylene ether is 1:3.3, and the type of the reactive emulsifier is LRS-10. The mass percentage concentration of the ammonia water in the step (6) is 25%. The initiator aqueous solution in the step (6) is a potassium persulfate aqueous solution, wherein the mass percentage concentration of potassium persulfate is 2.5%. The water used in steps (2) - (6) is deionized water.

The garlic residue-based liquid mulching film of the embodiment 2 can be obtained through the steps (1) to (6), the appearance of the garlic residue-based liquid mulching film is uniform and stable emulsion, and no layering phenomenon occurs after standing for 30 days.

Example 3

(2) mixing pregelatinized starch and water at 25 ℃ to form a starch slurry, wherein the mass ratio of the pregelatinized starch to the water is 0.18: 1;

(3) mixing the garlic residue slurry obtained in the step (1) with the starch slurry obtained in the step (2), and stirring for 3h at 25 ℃ and the stirring speed of 2000r/min to obtain the garlic residue-starch slurry, wherein the mass ratio of the garlic residue slurry to the starch slurry is 0.3: 1;

(4) adding the garlic residue-starch slurry obtained in the step (3) into a three-neck flask provided with a stirrer, a thermometer and a condenser, adding an oxidant aqueous solution into the flask while stirring at 85 ℃, wherein the stirring speed is 500r/min, and the stirring time is 1h, and then obtaining a pre-oxidized garlic residue-starch slurry, wherein the mass ratio of the garlic residue-starch slurry obtained in the step (3) to the oxidant aqueous solution is 4.7: 1;

(5) mixing the pre-oxidized garlic residue-starch slurry obtained in the step (4) with an acrylic acid monomer mixture, an emulsifier and water, and pre-emulsifying the obtained mixture for 30min at 50 ℃ and at a stirring speed of 1500r/min to obtain a pre-emulsified mixture, wherein the mass ratio of the pre-oxidized garlic residue-starch slurry obtained in the step (4) to the acrylic acid monomer mixture to the emulsifier to the water is 17: 8: 1: 27;

(6) raising the temperature of the pre-emulsified mixture obtained in the step (5) to 80 ℃, and dropwise adding an initiator aqueous solution into the pre-emulsified mixture at a dropping speed of 0.12mL/min while stirring, wherein the mass ratio of the pre-emulsified mixture obtained in the step (5) to the initiator aqueous solution is 5.23: 1; after the initiator is added dropwise, the reaction is continued for 5 hours at 80 ℃ and at a stirring speed of 350r/min, then the reaction system is cooled to room temperature, and the pH value of the system is adjusted to 7.0 by ammonia water, thus obtaining the emulsion which can be used as the garlic residue-based liquid mulching film.

Wherein the oxidant aqueous solution in the step (4) is ammonium persulfate aqueous solution, and the mass percentage concentration of the ammonium persulfate is 10%. The acrylic acid monomer mixture in the step (5) comprises butyl acrylate, methyl methacrylate and acrylic acid, wherein the mass ratio of the butyl acrylate to the methyl methacrylate to the acrylic acid is 6:3: 1. The emulsifier in the step (5) is a mixture of a reactive emulsifier and octylphenol polyoxyethylene ether (10), wherein the mass ratio of the reactive emulsifier to the octylphenol polyoxyethylene ether is 1:3, and the model of the reactive emulsifier is LRS-10. The mass percentage concentration of the ammonia water in the step (6) is 25%. The initiator aqueous solution in the step (6) is an ammonium persulfate aqueous solution, wherein the mass percentage concentration of ammonium persulfate is 2.8%. The water used in steps (2) - (6) is deionized water.

The garlic residue-based liquid mulching film of the embodiment 3 can be obtained through the steps (1) to (6), the appearance of the garlic residue-based liquid mulching film is uniform and stable in emulsion shape, and the layering phenomenon does not occur within 30 days.

Example 4

(2) mixing pregelatinized starch and water at 35 ℃ to form a starch slurry, wherein the mass ratio of the pregelatinized starch to the water is 0.21: 1;

(3) mixing the garlic residue slurry obtained in the step (1) with the starch slurry obtained in the step (2), and stirring at 25 ℃ for 5h at a stirring speed of 3000r/min to obtain a garlic residue-starch slurry, wherein the mass ratio of the garlic residue slurry to the starch slurry is 0.6: 1;

(4) adding the garlic residue-starch slurry obtained in the step (3) into a three-neck flask provided with a stirrer, a thermometer and a condenser, adding an oxidant aqueous solution into the flask while stirring at 90 ℃, wherein the stirring speed is 200r/min, and the stirring time is 2h, and then obtaining a pre-oxidized garlic residue-starch slurry, wherein the mass ratio of the garlic residue-starch slurry obtained in the step (3) to the oxidant aqueous solution is 5.8: 1;

(5) mixing the pre-oxidized garlic residue-starch slurry obtained in the step (4) with an acrylic acid monomer mixture, an emulsifier and water, and pre-emulsifying the obtained mixture for 120min at the temperature of 60 ℃ and the stirring speed of 5000r/min to obtain a pre-emulsified mixture, wherein the mass ratio of the pre-oxidized garlic residue-starch slurry obtained in the step (4) to the acrylic acid monomer mixture to the emulsifier to the water is 21: 11: 1: 21;

(6) raising the temperature of the pre-emulsified mixture obtained in the step (5) to 90 ℃, and dropwise adding an initiator aqueous solution into the pre-emulsified mixture at a dropping speed of 0.3mL/min while stirring, wherein the mass ratio of the pre-emulsified mixture obtained in the step (5) to the initiator aqueous solution is 5.6: 1; after the initiator is added dropwise, the reaction is continued for 8 hours at the temperature of 90 ℃ and the stirring speed of 500r/min, then the reaction system is cooled to the room temperature, and the pH value of the system is adjusted to 9.0 by ammonia water, thus obtaining the emulsion which can be used as the garlic residue-based liquid mulching film.

Wherein the oxidant aqueous solution in the step (4) is a potassium persulfate aqueous solution, and the mass percentage concentration of the potassium persulfate is 12%. The acrylic acid monomer mixture in the step (5) comprises butyl acrylate, methyl methacrylate and acrylic acid, wherein the mass ratio of the butyl acrylate to the methyl methacrylate to the acrylic acid is 6.5:2.5: 1. The emulsifier in the step (5) is a mixture of a reactive emulsifier and octylphenol polyoxyethylene ether (10), wherein the mass ratio of the reactive emulsifier to the octylphenol polyoxyethylene ether is 1:3.5, and the type of the reactive emulsifier is LRS-10. The mass percentage concentration of the ammonia water in the step (6) is 25%. The initiator aqueous solution in the step (6) is a potassium persulfate aqueous solution, wherein the mass percentage concentration of potassium persulfate is 3.1%. The water used in steps (2) - (6) is deionized water.

The garlic residue-based liquid mulching film of the embodiment 4 can be obtained through the steps (1) to (6), the appearance of the garlic residue-based liquid mulching film is uniform and stable emulsion, and no layering phenomenon occurs after standing for 30 days.

Comparative example 5

This example was a liquid mulching film prepared according to the procedure described in example 3, and differs from example 3 in that the mass ratio between the garlic residue slurry and the starch slurry in step (3) was 0.65 (or 0.3: 0.46), which is greater than the range (0.09-0.6) described in the claims of the present invention: except 1, i.e., the amount of starch slurry used in comparative example 5 was small. The other preparation steps and the amounts of reagents were the same as in example 3.

Comparative example 6

This example was carried out to prepare a liquid mulching film according to the procedure of example 3, and differs from example 3 in that the mass ratio between the amount of the garlic residue slurry and the amount of the starch slurry in step (3) was 0.06 (or 0.06: 1), which is within the range of the claims of the present invention (0.09-0.6): except 1, the garlic clove residue slurry used in comparative example 6 was used in a smaller amount. The other preparation steps and the amounts of reagents were the same as in example 3.

Comparative example 7

This example was carried out to prepare a liquid mulch according to the procedure described in example 3, and differs from example 3 in that no aqueous oxidant solution was added in step (4). The other preparation steps and the amounts of reagents were the same as in example 3. The specific test steps are as follows:

the preparation steps (1) to (3) of this example are the same as the steps (1) to (3) of example 3.

(4) And (4) adding the garlic residue-starch slurry obtained in the step (3) into a three-neck flask provided with a stirrer, a thermometer and a condenser. Then stirring the garlic residue-starch slurry at 85 ℃ at the stirring speed of 500r/min for 1h to obtain non-preoxidized garlic residue-starch slurry;

(5) mixing the non-pre-oxidized garlic residue-starch slurry obtained in the step (4) with an acrylic acid monomer mixture, an emulsifier and water, and pre-emulsifying the obtained mixture for 30min at 50 ℃ and at a stirring speed of 1500r/min to obtain a pre-emulsified mixture, wherein the mass ratio of the non-pre-oxidized garlic residue-starch slurry obtained in the step (4) to the acrylic acid monomer mixture to the emulsifier to the water is 17: 8: 1: 27;

the remaining preparation procedure of this example was the same as the preparation procedure (6) of example 3.

Wherein the acrylic acid monomer mixture in the step (5) comprises butyl acrylate, methyl methacrylate and acrylic acid, and the mass ratio of the butyl acrylate to the methyl methacrylate to the acrylic acid is 6:3: 1. The emulsifier in the step (5) is a mixture of a reactive emulsifier and octylphenol polyoxyethylene ether (10), wherein the mass ratio of the reactive emulsifier to the octylphenol polyoxyethylene ether is 1:3, and the model of the reactive emulsifier is LRS-10. The mass percentage concentration of the ammonia water in the step (6) is 25%. The initiator aqueous solution in the step (6) is an ammonium persulfate aqueous solution, wherein the mass percentage concentration of ammonium persulfate is 2.8%. The water used in steps (2) - (6) is deionized water.

Comparative example 8

This example was a liquid mulching film prepared according to the procedure described in example 3, and differs from example 3 in that the mass ratio between the four of the pre-oxidized garlic residue-starch slurry, the acrylic acid monomer mixture, the emulsifier and the water in step (5) was 17: 3: 1: 27 in the range (14-21) according to the claims of the present invention: (5-11): 1: (13-27) except for the above, the amount of the acrylic monomer mixture used is small. The other preparation steps and the amounts of reagents were the same as in example 3.

Comparative example 9

This example was a liquid mulching film prepared according to the procedure described in example 3, and differs from example 3 in that the mass ratio between the four of the pre-oxidized garlic residue-starch slurry, the acrylic monomer mixture, the emulsifier and the water in step (5) was 12: 8: 1: 27 in the range (14-21) according to the claims of the present invention: (5-11): 1: (13-27) except for the pre-oxidized garlic residue-starch slurry, the amount of the pre-oxidized garlic residue-starch slurry is small. The other preparation steps and the amounts of reagents were the same as in example 3.

Application example 10

In this example, the garlic residue-based liquid mulching film emulsion obtained in examples 1 to 4 was sprayed on the soil surface to be used as an agricultural liquid mulching film, and the specific test steps were as follows:

(1) selecting a vegetable planting field, wherein the places are east longitude: 118.98385532736967 ° and north latitude: 32.06034538505579 deg. planting Chinese cabbage in the field;

(2) dividing the field into 5 fields with the size of 0.5m multiplied by 0.5m in 9 months of 2020, wherein the interval between every two fields is 0.1 m; uniformly sowing 30 Chinese cabbage seeds in each field; then 0.58kg/m to 4 fields²The garlic residue-based liquid mulching film emulsions obtained in examples 1 to 4 were uniformly sprayed in the amounts of the respective fields, and the 5 th field was a field not sprayed with any emulsion as a control group.

Effects of the embodiment

This example was conducted to the following performance tests of the garlic clove basilar membrane emulsions prepared in examples 1 to 4 and the liquids prepared in comparative examples 5 to 9, respectively.

1. Emulsion stability test

Observing whether the sample is layered within 30 days, and if the sample is not layered, indicating that the emulsion has stability, and carrying out the following test; if the delamination phenomenon occurs, the sample is unstable and is not suitable for being used as liquid mulching film emulsion, and the sample does not enter the subsequent testing link.

2. Viscosity measurement

The viscosity of the liquid was measured using an NDJ-1 rotational viscometer (Nihonun Intelligent science Co., Ltd., Shanghai, China). The temperature of each sample was maintained at 30 ℃ during the test, and the rotation speed was controlled at 60 r/min. Viscosity values are reported in mpa.s.

3. Sprayability test

The sprayability of the liquid samples was tested using a hand-held spray gun. The inner diameter of the spray gun is 2.5mm, the air pressure when the liquid is sprayed by the spray gun is 0.3MPa, if the spraying distance of the emulsion under the condition can be more than 200mm, the emulsion is considered to have sprayability, otherwise, the emulsion does not have sprayability.

4. Soil temperature and humidity test

Testing of soil temperature: the temperature at the soil depth of 5cm in each field in application example 10 was measured using a curved tube thermometer (beijing dingshengrong and science and technology limited, china) for 14:00-16:00 days, and the test was continued for 30 days, and the average temperature during this test period was used as a report value.

Testing the water content of the soil: the soil temperature is measured, 5 g of soil with the soil layer depth of 5cm in each field is taken at the same time, the water content of the soil is measured by adopting a drying method, namely, the taken 5 g of soil is dried at 80 ℃, and then the soil is calculated according to a formula: the soil moisture content was [ (5-soil mass after drying)/5 ] × 100%, and the test was performed every 2 days for 30 days, and the average moisture content of the soil during this test period was used as a report value.

5. Cabbage yield test

When one growth period of the pakchoi in each field of application example 10 was over (2 months), the pakchoi were taken out from the field together with their roots, and the soil attached to the roots was gently swept off with a brush. And then weighing all the pakchoi produced in each field, and evaluating the influence of the garlic residue-based liquid mulching film on the yield of the pakchoi in each field according to the yield of the pakchoi in each field.

6. Experiment for resisting Plutella xylostella

The anti-cabbage moth experimental tests were carried out in a greenhouse environment (25 ℃, 35% humidity) and are expressed as the effect of cabbage moths on the dry weight of cabbage seedlings. The Plutella xylostella is collected from a farm, the collected Plutella xylostella is firstly raised with fresh cabbage for two days to eliminate the influence of original food storage in the larvae on subsequent experiments, and then 30 larvae with similar body types are selected and divided into 3 groups of 10 larvae.

Transplanting the young seedlings of the pakchoi with the similar weight and appearance into 4 identical flowerpots. Each flowerpot is 10cm in diameter and 5cm in depth and is filled with 200g of soil powder obtained by sieving with a 5-mesh sieve; each flowerpot comprises 4 plantlets of pakchoi. Then, the emulsions according to example 3, comparative example 6 and comparative example 9 were uniformly sprayed on the soil surface of each pot, respectively, 3 pots were placed in the same greenhouse, a group (10) of cabbage moths were placed in each pot, and the entire body of each pot and the cabbage seedlings in the pots was covered with a white nylon gauze (100 mesh), which was used to prevent the cabbage moths from moving between the cabbage seedlings in different pots and affecting the experimental results. After the 10 th day, the leaf breakage of the young leaf of the pakchoi was observed, and then the pakchoi was taken out from each pot together with the root, the soil attached to the root of the pakchoi was gently removed with a brush, and dried at 80 ℃ for 48 hours, and the young seedling of the pakchoi dried in each pot was weighed.

7. As can be seen from Table 1, no delamination occurred within 30 days for any of the emulsions prepared in examples 1-4, indicating that the emulsions prepared in examples 1-4 were stable. In addition, the emulsions prepared in comparative examples 6, 7 and 9 also did not exhibit emulsion creaming, indicating that the emulsions prepared in these examples are also stable. While the sample prepared in comparative example 5 showed delamination at day 10, indicating that the sample was unstable; this is explained as follows: because the starch pulp has certain viscosity and suspension effect, the garlic residue particles are suspended in the starch colloid and are uniformly mixed with starch molecular chains, so that the garlic residue is not easy to settle and has layering phenomenon; however, the amount of the starch slurry in comparative example 5 is less than the scope of the claims, which makes it difficult for the starch colloid in comparative example 5 to exert the effect of suspending and preventing the sedimentation of the garlic residue particles. The liquid sample prepared in comparative example 8 also showed delamination at day 4, indicating that the liquid sample of this example was also unstable; the acrylic acid monomer mixture comprises butyl acrylate, methyl methacrylate and acrylic acid which are monomers with carbon-carbon double bonds and can be subjected to free radical polymerization reaction under the action of an initiator, the acrylic acid monomers can be bonded with garlic residues and starch molecules in the polymerization reaction to form a polymer with a larger molecular weight, and the formation of the polymer can fix garlic residue particles in a network formed by a three-dimensional polymer chain, so that the garlic residue particles are more easily suspended in a liquid system, the garlic residue particles are prevented from settling, and the liquid is prevented from layering; the acrylic monomer mixture of comparative example 8 was used in a small amount, which caused that it did not form a polymer chain network in a sufficient amount to hinder the aggregation and sedimentation of the garlic clove particles. In conclusion, the samples prepared in comparative example 5 and comparative example 8 are easily delaminated, the heterogeneous liquid can block the nozzle when being used for spraying operation, and the liquid mulching film with uniformly distributed components can not be formed on the soil surface, so the samples of comparative example 5 and comparative example 8 can not be used as the liquid mulching film product, and the samples do not need to enter the later testing link.

As can be seen from Table 2, the emulsions of examples 1-4 and comparative examples 6 and 9 all have sprayability, which is related to the lower viscosity of their emulsions (viscosity range 392-500 mPas); the emulsion with low viscosity has small association among molecular chains in the emulsion, so under the action of certain air pressure, all components in the emulsion can smoothly pass through a nozzle of a spray gun, emulsion liquid drops are easy to disperse and move forwards at a high speed in a mist mode, and the emulsion can be distributed on the surface of soil to form a uniform liquid mulching film with a larger spraying area and a more uniform mode. While the liquid viscosity (1327mPa · s) of comparative example 7 is much higher than that of the samples of other examples, and it has no sprayability, this is because the liquid preparation step of comparative example 7 does not undergo a pre-oxidation step in which an oxidizing agent is added, which can oxidize a part of the hydroxyl groups in the garlic residue and starch into carboxyl groups, this can reduce the association between the system molecules caused by hydrogen bonds to some extent, and helps to reduce the viscosity of the system, therefore, the liquid of comparative example 7, which was not subjected to pre-oxidation, had a large viscosity due to the large association between the molecular chains in the liquid of comparative example 7, the liquid having a large viscosity encountered a large resistance when passing through the nozzle of the spray gun, the spraying distance was short, and the liquid droplets were not easily dispersed in a mist form to move forward, and therefore the sample of comparative example 7 was not suitable for use as a liquid mulching film.

The results in Table 3 show that in application example 10, the soil temperature of the field to which the emulsions of examples 1 to 4 were respectively applied was 2.32 to 2.47 ℃ higher than that of the field to which no emulsion was applied; meanwhile, the soil water content of the soil with the depth of 5cm corresponding to the former is 7.28-9.39% higher than that of the soil with the latter; the yield of the pakchoi corresponding to the embodiments 1-4 is 34.3-57.9% higher than that of the pakchoi which is not sprayed with any emulsion. This shows that the liquid mulching films prepared in examples 1 to 4 within the scope of the claims have better effects of keeping warm and moisture of agricultural soil and increasing the yield of pakchoi.

The results in Table 4 show that in the experiment against Plutella xylostella, the yield of the pakchoi in the pot corresponding to example 3 was 0.17Kg, whereas the yields of the pakchoi in the pots corresponding to comparative example 6 and comparative example 9 were 64.7% and 35.3% lower than those of example 3, respectively. The liquid mulch film of example 3 contains a suitable amount of garlic pomace, which, as previously mentioned, is a natural biological agent that kills pests and germs that can harm crops, so the activity of the diamondback moth in the field of example 3 is inhibited, i.e., the diamondback moth has little infestation on the pakchoi. And the ratio of the mass of the garlic residue slurry and the starch slurry of step (3) in comparative example 6 is only 0.06 (or 0.06: 1), which is within the range (0.09-0.6) of the claims of the present invention: except for 1, that is, the garlic clove residue slurry used in comparative example 6 was used in a small amount. The mass ratio of four of the pre-oxidized garlic residue-starch slurry, the acrylic acid monomer mixture, the emulsifier and the water in the step (5) of comparative example 9 was 12: 8: 1: 27 in the range (14-21) according to the claims of the present invention: (5-11): 1: (13-27) except for the pre-oxidized garlic residue-starch slurry, the amount of the pre-oxidized garlic residue-starch slurry is small. Since the content of the garlic residue in the liquid mulching film product is reduced in comparative example 6 and comparative example 9, and the content of allicin capable of repelling insects in the product is correspondingly reduced, the activity of the product for inhibiting the cabbage moth is reduced, so that the cabbage seedlings corresponding to comparative example 6 and comparative example 9 are invaded by the cabbage moth more, and the yield of the cabbage is correspondingly reduced more.

Table 1 the stability of the emulsions obtained in examples 1 to 4 and comparative examples 5 to 9 was evaluated by recording whether the emulsions delaminated within 30 days.

Table 2 viscosity and sprayability of the emulsions prepared in examples 1 to 4 and comparative examples 6, 7 and 9.

Sample (I)	Viscosity of the emulsion	Sprayability
			Example 1	500mPa·s	Sprayable
Example 2	465mPa·s	Sprayable
			Example 3	417mPa·s	Sprayable
Example 4	458mPa·s	Sprayable
			Comparative example 6	401mPa·s	Sprayable
Comparative example 7	1327mPa·s	Can not be sprayed
			Comparative example 9	392mPa·s	Sprayable

Table 3 average soil temperature, average soil moisture content and yield of pakchoi in application example 10, each field to which liquid mulch emulsions of examples 1-4 were applied and to which no emulsion was applied.

Table 4 effects example 3, comparative example 6, and comparative example 9 were tested against cabbage moth and evaluated with respect to the weight of the dried plantlets of pakchoi in the pots corresponding to each example.

Claims

1. A preparation method of a garlic residue-based liquid mulching film is characterized in that the garlic residue-based liquid mulching film is prepared from the following main raw materials: the preparation method of the garlic residue slurry, the pregelatinized starch and the acrylic acid monomer mixture comprises the following steps:

2. The preparation method according to claim 1, wherein the aqueous solution of the oxidizing agent in the step (4) is an aqueous solution of potassium persulfate or ammonium persulfate, and the mass percentage concentration of the potassium persulfate or the ammonium persulfate is 6 to 12 percent.

3. The method according to claim 1, wherein the acrylic monomer mixture in the step (5) comprises butyl acrylate, methyl methacrylate and acrylic acid, wherein the mass ratio of the butyl acrylate to the methyl methacrylate to the acrylic acid is (5.5-6.5): (2.5-3.5): 1.

4. the preparation method according to claim 1, wherein the emulsifier in the step (5) is a mixture of a reactive emulsifier and octylphenol polyoxyethylene ether (10), and the mass ratio of the reactive emulsifier to the octylphenol polyoxyethylene ether (10) is 1: (2.5-3.5), and the type of the reactive emulsifier is LRS-10.

5. The production method according to claim 1, wherein the concentration of the aqueous ammonia in the step (6) is 25% by mass.

6. The preparation method according to claim 1, wherein the aqueous initiator solution in the step (6) is an aqueous solution of potassium persulfate or ammonium persulfate, and the mass percentage concentration of the potassium persulfate or the ammonium persulfate is 2.2 to 3.1 percent.

7. The method according to claim 1, 2, 5 or 6, wherein the water is deionized water.

8. A garlic dreg-based liquid mulching film prepared by the preparation method as claimed in any one of claims 1 to 7.

9. The use of the garlic clove residue based liquid mulching film of claim 8 in agricultural liquid mulching film.