CN113388167A

CN113388167A - Hydrophobic degradable liquid mulching film and preparation method thereof

Info

Publication number: CN113388167A
Application number: CN202110705217.2A
Authority: CN
Inventors: 李培强; 孙明胜; 姜春欣; 张昱; 宋文瀚
Original assignee: Shandong Shike Chenglong Biotechnology Co ltd; Shandong Agricultural University
Current assignee: Shandong Shike Chenglong Biotechnology Co ltd; Shandong Agricultural University
Priority date: 2021-06-24
Filing date: 2021-06-24
Publication date: 2021-09-14

Abstract

The invention discloses a degradable liquid mulching film and a preparation method thereof, belonging to the field of agricultural mulching films. A degradable liquid mulching film mainly comprises a macromolecular material subjected to hydrophobic modification; the whole mulching film material exists in a liquid state, can be directly sprayed on soil to form a film when in use, can be degraded and improve the scouring resistance of the mulching film due to the adoption of the polymer material subjected to hydrophobic modification, realizes water retention and soil moisture preservation of the soil, and can be directly sprayed to form a film along with the sowing of seeds, so that the labor intensity of farmers is greatly reduced, and the use cost is reduced.

Description

Hydrophobic degradable liquid mulching film and preparation method thereof

Technical Field

The invention relates to the technical field of agricultural mulching films, in particular to a degradable liquid mulching film and a preparation method thereof.

Background

In the face of the severe land form of China, the mode of planting crops by using plastic mulching films becomes a mode commonly adopted by farmers; the plastic mulching cultivation technology is used for preserving heat, preserving soil moisture and maintaining fertility of crops, achieves the purposes of increasing production and income, and becomes one of ten agricultural popularization and application technologies in the world today. In the past decades, traditional agricultural plastic mulching films have made great contributions to the structural adjustment of agricultural industries in China and the increase in both production and income of crops. With the adjustment of agricultural industrial structure and the popularization of agricultural technology in China, the use of the mulching film for increasing the yield and income of crops is accepted by vast farmers; however, the plastic mulching film is made of polyethylene or polyvinyl chloride which has excellent physical properties, is tough and durable, is light and cheap, and cannot be degraded under natural conditions after being discarded for one hundred years. The mulching film products are difficult to recycle after being used and are discarded in soil, and serious white pollution to the soil and the environment is caused in the year-on-month period. With the perennial use of polyethylene mulching films, the residual films in the soil bring serious pollution to the soil and living environment, which is a global problem. At present, the use residue of a large amount of plastic mulching films seriously damages the whole ecological environment, and the damage is mainly expressed in the following three aspects:

1) modification of plastic residual film to soil property

As the plastic residual film has large surface area, the mutual combination of soil layers is blocked, and the integrity and permeability of the soil are damaged, the correlation determination analysis shows that the volume weight of the soil and the plastic residual film amount are in obvious positive correlation, and the moisture content and the porosity are in obvious negative correlation. Test results show that the plastic mulching film is remained in the soil to deteriorate the physical properties of the soil. Mainly manifested by the decrease of infiltration and infiltration coefficients under soil moisture. The plastic fragments have significant influence on the volume weight of soil, the water content of the soil, the porosity of the soil, the air permeability of the soil and the like. The larger the residual debris, the heavier the impact. The residual films in the farmland are mostly gathered on the soil plough layer and the surface layer, so that the movement of soil capillary water and the infiltration of precipitation are more easily hindered. Due to the obstruction of the plastic agricultural film fragments, the operation of soil moisture, nutrients and air is hindered.

2) Effect of residual Plastic mulch on crop growth

Originally, the mulching film is used for increasing the yield and income and increasing the yield of crops, but a large amount of agricultural plastic mulching film is left in soil to form a barrier layer and hinder the development of crop root systems and the absorption of moisture and nutrients, so that the growth development and the yield of the crops are influenced, and particularly the influence on the fibrous root type crops is most obvious. The plastic mulching film is remained in the soil, so that the emergence rate of the wheat field is reduced, the seedling death rate is increased, the distribution form of plant root systems in the soil is changed, the depth of main root penetration is influenced, the root systems are not beneficial to absorption and utilization of deep water in the soil, and the yield is reduced to a certain degree. According to investigation, the yield reduction of the perennial plastic film mulching farmland crops reaches 10 to 15 percent.

3) Pollution of plastic mulching film to soil, crops and environment

In the production process of the plastic agricultural film, in order to keep the agricultural mulching film stable under the temperature change and the sunlight irradiation, heavy metal salts containing Pb, Cd, Zn, Ba, Sn and the like and some valuable compounds are often added, and compounds mainly containing Pb and Cd are used as stabilizers, so that the heavy metals are easily dissolved out from the agricultural film in the re-covering process and enter soil, the soil is continuously polluted by the heavy metals, and the accumulation is generated in crops, thereby affecting the quality of agricultural products. In addition, the agricultural plastic film is a polyethylene compound, 40-60% of plasticizer, namely dibutyl phthalate, is required to be added in the production process, the compound such as the plasticizer has high toxicity to the growth and development of plants, the chloroplast formation of crops is damaged, and leaves are green and white, so that the yield is reduced, and particularly, the agricultural plastic film has high toxicity to vegetables. The recovery rate of the waste mulching films of the farmland is less than 10 percent; the resource and environment protection station of the Xinjiang agricultural hall continuously samples and surveys 20 counties of Sinkiang farmlands. The investigation result shows that the average residual mulching film amount per mu already reaches 16.88 kilograms, while in some towns in the southern Xinjiang area, the residual mulching film amount even reaches more than 40 kilograms, and the quantity is equivalent to 10 layers of mulching films paved on the farmland according to 4 kilograms of mulching films paved on each mu per year. Today, the "white revolution" has evolved gradually into a surprise "white disaster".

In order to solve the above problems, scientists have proposed that degradable liquid mulching films are used to replace the plastic mulching films, and at present, there are many units and individuals researching and applying the degradable liquid mulching films at home and abroad, but at present, the liquid mulching films are generally made of extremely hydrophilic materials such as humic acid, cellulose, starch, ethyl cellulose, polyglutamic acid and the like, or polymer materials are simply mixed with the hydrophilic materials, and the materials basically cannot form films but are simple chemical mulching. Even if the mulching film is formed, the performance of the mulching film is poor, the mulching film is not elastic and fragile, the mulching film is not resistant to rain wash, and the lasting period of the material is very poor, so that how to provide the degradable liquid mulching film which is excellent in performance and suitable for popularization becomes a problem to be solved in the field.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provides a degradable liquid mulching film and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

a degradable liquid mulching film mainly comprises a polymer material subjected to hydrophobic modification, wherein the polymer material is selected from one or more of chitin, polycarbonate, alkyl glucoside, coco glucoside, cellulose acetate and carboxymethyl cellulose.

Chitin is safe, nontoxic, and has good film forming property, air permeability and biocompatibility. It can form film on the surface of object, and because the film is stereo net structure, various moisture-retaining factors and physiological functional substances can be embedded in the film, and it has continuous slow-release action.

Polycarbonate is a raw material of general engineering plastics. Has the following characteristics: (a) has high strength and elastic coefficient, high impact strength and wide application temperature range; (b) low molding shrinkage and good dimensional stability.

Alkyl glucoside: has the characteristics of stability, no toxicity, solubility, easy biodegradation, low irritation to skin and the like. Has the advantages of high surface activity, high viscosity, rich foam, fineness and stability

Coco glucoside: solubility: and (3) water-soluble stability: and (4) stabilizing. Biodegradability: can be degraded.

The cellulose acetate is used as a porous membrane material, and has the characteristics of high selectivity, large water permeability, simple processing and the like. (a) No toxicity, no harm, no allergy after long-term skin contact. (b) Fibrous, plastic; (c) easily bonded together with a plasticizer, heat, or pressure;

the carboxymethyl cellulose has the functions of thickening, filming, adhering, water maintaining, colloid protecting, emulsifying and suspending

Preferably, the hydrophobically modified polymer material is one or a combination of more of polymer materials subjected to esterification modification, etherification modification, hydroxyalkylation modification, graft copolymerization modification or crosslinking modification. Through the modification process, the original hydrophilicity of the high polymer material is modified into the hydrophobicity high polymer material.

Preferably, the hydrophobizing agent for hydrophobically modifying the high molecular material is long-chain alkane or aromatic hydrocarbon.

Preferably, the hydrophobizing agent is carboxylic acid, epoxy compound, halogenated hydrocarbon, aliphatic acyl chloride, isocyanate, and amine compound, and the polymer material corresponds to the hydrophobizing agent one by one.

A preparation method of a degradable liquid mulching film mainly comprises the following steps:

s1, weighing the high polymer material and water in the ratio of 1: 2 heating the mixture to 50-60 ℃ in water for dispersion, adding a hydrophobization reagent for hydrophobization modification to obtain a hydrophobically modified high polymer material;

s2, weighing the hydrophobically modified high polymer material obtained in the step S1, adding a surfactant and a photocatalyst, and uniformly stirring with water to obtain a colloidal viscous transparent liquid mulching film. The component proportion of the surfactant, the photosensitive catalyst and the hydrophobically modified high polymer material is 0.05: 0.02: 1.

the surfactant is selected from anionic surfactant of two combinations of sodium dodecyl benzene sulfonate and calcium dodecyl benzene sulfonate (15:1), cationic surfactant of quaternary ammonium compound: zwitterionic surfactants of two combinations of N-acyl sarcosines, betaine-type active agents (1: 1): c12-18 alkyl glucoside, fatty acid sorbitol, and styrene phenol polyoxyethylene ether (2:1: 3). 8 percent of the total amount of the surfactant, 1:1 of the mass ratio of the cationic surfactant to the anionic surfactant, 2-4 percent of the cationic surfactant and 0-4 percent of the zwitterionic surfactant.

The sodium dodecyl benzene sulfonate is neutral, is sensitive to water hardness, is not easy to oxidize, has strong foaming power and high detergency, is easy to be compounded with various auxiliaries, has lower cost, mature synthesis process and wide application field, and is an excellent anionic surfactant. The sodium dodecyl benzene sulfonate is used as an anionic surfactant, has good surface activity and stronger hydrophilicity, effectively reduces the tension of an oil-water interface, and achieves the emulsification effect.

Calcium dodecylbenzenesulfonate, also called pesticide emulsifier 500#, is mainly used for preparing mixed pesticide emulsifiers, textile oil agents, tile detergent, grinding oil agents, cement dispersants, etc. And an emulsifier is provided for later pesticide addition and drug film integration.

The N-acyl sarcosinate is a chemical product with excellent decontamination, foaming and emulsification functions. Has strong compatibility with various surfactants and mild bactericidal action.

The betaine type surfactant is composed of a quaternary ammonium salt type cation part and a carboxylate type anion part, has better performance than an amino acid type amphoteric surfactant, and is prepared by reacting fatty tertiary amine with sodium chloroacetate. The N-alkyl betaine has good wettability and emulsibility, excellent antistatic property, mature production process and simple equipment. The N-long chain acyl alkylidene betaine has the characteristics of disinfection, sterilization, low irritation and the like. The N-long-chain thiocarboxylic acid type betaine has good antibacterial property and can inhibit the growth and the propagation of microorganisms.

The C12-18 alkyl glucoside is an alkyl glucoside, and belongs to a surfactant. Has excellent cleaning effect, certain thickener, relatively mild and relatively low irritation to skin.

The sorbitol fatty acid ester has the performance and emulsification effect of mixing with various surfactants, has mature manufacturing process technology, can be applied to a series of oil-soluble liquid or wax-like compounds in the industries of food, medicine, cosmetics, textile and the like, and is suitable for being used as a water-in-oil (W/O) emulsifier. Is beneficial to the combination of water and oil, is not easy to be layered and is uniformly mixed.

Styrylphenol polyoxyethylene ether is a nonionic surfactant. The properties are the same as emulsifier BP. Used as the main component of the organophosphorus pesticide emulsifier, and further reduced.

A photosensitive catalyst: metalloporphyrin

The proton on the nitrogen of the porphyrin inner ring is unstable. The metal ion is combined with the proton of the inner pyrrole to be converted into metalloporphyrin. Subsequent intensive research on the rate and mechanism of metalloporphyrin formation and decomposition, ligand reaction at the metalloporphyrin metal center, and other chemical characteristics by scientists has resulted in the finding that porphyrin and metalloporphyrin systems exhibit good performance in redox reactions. It has the function of eliminating external interference. And has excellent carbon dioxide adsorption capacity and light conversion capacity and excellent development potential.

Compared with the prior art, the invention provides a degradable liquid mulching film and a preparation method thereof, and the degradable liquid mulching film has the following beneficial effects:

1. according to the degradable liquid mulching film and the preparation method thereof, the whole mulching film material exists in a liquid state, and can be directly sprayed on soil to form a film in a spraying manner during use.

2. According to the degradable liquid mulching film and the preparation method thereof, water-soluble fertilizers and water-soluble medicines beneficial to crops, such as water-soluble fertilizers and various water-soluble pesticides and herbicide medicines, are further added into the whole liquid mulching film system, so that the liquid mulching film integrating the pesticide film and the fertilizer film is obtained, the additional value of the liquid mulching film is further improved, the pesticide-fertilizer integrated application is realized, the labor intensity is greatly reduced, and the effect of simultaneously taking effect of the pesticide and the fertilizer is realized, which is an effect difficult to achieve by the existing plastic mulching film.

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.

A degradable liquid mulching film mainly comprises a polymer material subjected to hydrophobic modification.

The high molecular material is chitin, polycarbonate, alkyl glucoside, coco glucoside, cellulose acetate, and carboxymethyl cellulose.

The hydrophobic modified high polymer material is a high polymer material which is subjected to esterification modification, etherification modification, hydroxyalkylation modification, graft copolymerization modification or crosslinking modification.

The hydrophobization reagent for carrying out hydrophobic modification on the high molecular material is long-chain alkane or aromatic hydrocarbon.

The hydrophobizing agent is carboxylic acid, epoxy compound, halogenated hydrocarbon, aliphatic acyl chloride, isocyanate, and amine compound.

s1, weighing the high polymer material, dispersing the high polymer material with hot water, and adding a hydrophobization reagent to carry out hydrophobization modification to obtain a hydrophobically modified high polymer material;

s2, weighing the hydrophobically modified high polymer material obtained in the step S1, adding a surfactant and a photocatalyst, and uniformly stirring with deionized water to obtain the colloidal viscous transparent liquid mulching film.

A photosensitive catalyst: metalloporphyrin

The whole mulching film material exists in a liquid state, can be directly sprayed on soil to form a film when in use, can be degraded and improve the flushing resistance of the mulching film due to the adoption of the polymer material subjected to hydrophobic modification, realizes water retention and soil moisture preservation of the soil, and can be directly sprayed and formed into a film along with the sowing of seeds, so that the labor intensity of farmers is greatly reduced, and the use cost is reduced;

by further adding water-soluble fertilizers and water-soluble medicines beneficial to crops, such as water-soluble fertilizers and various water-soluble pesticides and herbicide medicines, into the whole liquid mulching film system, the liquid mulching film integrating the pesticide film and the fertilizer film is obtained, the additional value of the liquid mulching film is further improved, the pesticide-fertilizer integrated application is realized, the labor intensity is greatly reduced, and the effect of simultaneously taking effect of the pesticide and the fertilizer is realized, which is an effect difficult to achieve by the existing plastic mulching film;

the modified polymer material and the auxiliary agent are in weak acidity after being added into water, most of the conventional herbicides or insecticides are in weak acidity, so that the modified polymer material and the auxiliary agent are matched for use, the performance of the liquid mulching film cannot be influenced, the pesticide effect cannot be adversely influenced, the pesticide cannot be easily lost due to the protection of the liquid mulching film, the modified polymer material can be better acted on plants, and can be directly sprayed with the liquid mulching film, so that the modified polymer material and the auxiliary agent are time-saving and labor-saving, the modified polymer material and the auxiliary agent are not easily lost under the protection of the liquid mulching film, the use amount can be obviously reduced compared with the single use, the modified polymer material and the auxiliary agent accord with the national environmental protection policy, and the food safety is better ensured.

When the liquid mulching film provided by the invention is used, only water needs to be added for dilution, so that the high polymer material can be better dispersed in the water instead of being dissolved, the film can be formed after spraying, and generally, in order to ensure the effect, the dilution ratio is generally controlled in the quality of the liquid mulching film: the mass of water is 1: 4-1: 6.

the following tests for the film performance by liquid casting film formation were carried out, and the following test results were obtained:

film stretching amount: cutting the size of the film into the same strip, fixing one end of the rubber band, pulling the other end of the film strip until the film is broken, and measuring the stretching length; taking 3 membrane strips of each sample as a group, and averaging; the film tensile values for the prepared samples ranged from 1 to 30 cm.

Water absorption of the film: taking a square film of 5cm multiplied by 5cm according to the national standard GB1034-70, drying the square film to constant weight at 105 ℃, then placing the square film in distilled water at room temperature, taking out the square film regularly, sucking surface moisture by using filter paper, weighing and calculating water absorption; taking 3 membrane strips as a group for each sample, and averaging, the result shows that the water absorption of the prepared sample is 2%, and the soil temperature is increased by 1-15 ℃.

Film light transmittance: making the diaphragm into a film strip with the length multiplied by the width of 3cm multiplied by 1cm, and measuring the light transmittance at the 660nm position of a 721 spectrophotometer; and 3 pieces of film strips are taken as a group for each sample, and the average value is taken, so that the light transmittance of the prepared sample is 30-99%.

Water retention of the film: filling 500g of air-dried sandy soil into a plastic bowl, adding 50mL of water, taking 2g of mulching film product, diluting with water by 20 times, and spraying, wherein only 50mL of water and the same mass of water are added to a control group for dilution; by adopting a regular weighing method, the result shows that the water retention rate of the soil can be improved by about 3-25% by preparing the sample.

The biodegradation performance of the film is as follows: cutting a film with a certain thickness into a shape with the size of 5cm multiplied by 5cm, burying the film under the surface layer of the soil by the depth of 10cm, taking out the film at regular intervals, observing the change of a detection sample, and completely degrading the sample in 240 days.

The performance of the liquid mulching film applied to the soil in combination with the technical scheme is further verified as follows:

taking a certain amount of liquid mulching film, diluting by 3-5 times, wherein the dilution ratio is determined by the pressure of the used spraying equipment, the pressure is 1.5-3kg, the liquid mulching film can be diluted by 4 times or more than 4 times, and the liquid mulching film can be diluted by 3 times or less more than 3 kg; according to the condition of soil particles, under the condition of covering with the traditional mulching film, the dosage per mu is 30-50 kg; 1-3 hours after spraying, the soil surface layer is completely solidified and bonded:

the soil after spraying is detected, and the result is as follows:

and (3) moisturizing: the moisture retention effect of the liquid mulching film is 2-10% higher than that of the plastic mulching film, and is 8-12% higher than that of the liquid mulching film without mulching film;

and (3) heat preservation: the heat preservation effect of the plastic mulching film is about 2-3 ℃ higher than that of the liquid mulching film, and the heat preservation effect of the liquid mulching film is about 4-5 ℃ higher than that of the non-mulching film;

the growth vigor of crops: the tobacco and garlic experiments covered by the liquid mulching film and the plastic mulching film show that the growth of crops is not influenced.

While the invention has been described above with reference to an embodiment, various modifications may be made and equivalents may be substituted without departing from the scope of the invention. In particular, as long as there is no conflict, the various features of the disclosed embodiments of the present invention can be used in any combination with each other, and the combinations are not exhaustively described in this specification only for the sake of brevity and resource conservation. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. The degradable liquid mulching film is characterized in that the main component of the degradable liquid mulching film comprises a polymer material subjected to hydrophobic modification, wherein the polymer material is selected from one or more of chitin, polycarbonate, alkyl glucoside, coco glucoside, cellulose acetate and carboxymethyl cellulose.

2. The degradable liquid mulching film according to claim 1, wherein the hydrophobically modified polymer material is a polymer material that is modified by esterification, etherification, hydroxyalkylation, graft copolymerization, or crosslinking.

3. The degradable liquid mulching film according to claim 1, wherein the hydrophobic agent for hydrophobically modifying the polymer material is selected from long-chain alkane or aromatic hydrocarbon, and the hydrophobic agent is selected from carboxylic acid, epoxy compound, halogenated hydrocarbon, aliphatic acyl chloride, isocyanate, and amine compound.

4. The degradable liquid mulching film according to claim 1, wherein the composition further comprises a water-soluble fertilizer and/or a water-soluble drug.

5. The preparation method of the degradable liquid mulching film is characterized by mainly comprising the following steps:

s1, weighing the high polymer material, dispersing the high polymer material in water at 50-60 ℃, adding a hydrophobizing reagent for hydrophobizing modification to obtain a hydrophobically modified high polymer material;

s2, weighing the hydrophobically modified high polymer material obtained in the step S1, adding a surfactant and a photocatalyst, and uniformly stirring with water to obtain a colloidal viscous transparent liquid mulching film.

The surfactant is selected from anionic surfactants of two combinations of sodium dodecyl benzene sulfonate and calcium dodecyl benzene sulfonate (15:1), and cationic surfactants of quaternary ammonium compounds: zwitterionic surfactants of two combinations of N-acyl sarcosines, betaine-type active agents (1: 1): c12-18 alkyl glucoside, fatty acid sorbitol, and styrene phenol polyoxyethylene ether (2:1: 3). Adding 8% of surfactant, adding 2-4% of cationic surfactant and 0-4% of anionic surfactant in a mass ratio of 1: 1; the photosensitive catalyst is metalloporphyrin.