CN107936507B - Mulching film for inhibiting weed growth and preparation method thereof - Google Patents

Abstract

A mulch film for inhibiting the growth of weeds, the mulch film is made of the following components in weight fraction: 100 parts of polylactic acid, 50-70 parts of polyadipate/butylene terephthalate, acetyl ethyl citrate 5-10 parts, antioxidants 0.1-1 parts, anti-ultraviolet additives 0.5-3 parts, carbon black masterbatch 5-10 parts. Using the adsorption function of carbon black, the herbicide is mixed into the carbon black, mixed by high-speed stirring, and then granulated under the action of the biodegradable resin carrier to make a carbon black masterbatch, and then added to the degradable mulch material in proportion for blow molding Film; since the herbicide enters into the internal voids of carbon black during the mixing process and is wrapped by carbon black, the herbicide will not be precipitated when the mulch film is blown.

Description

Mulch film for inhibiting weed growth and preparation method thereof

technical field

The invention relates to a mulch film for inhibiting the growth of weeds, which is mainly used for covering the mulch film, can effectively inhibit the growth of weeds, and belongs to the field of polymer material processing and application.

Background technique

With the development of the plastics industry, plastic products are more and more widely used. Among them, the agricultural plastic mulch used as crop covering is widely used because of its functions of heat preservation and moisture retention. However, the non-degradability of petroleum-based resins has caused great pollution to the soil environment. Therefore, there are many degradable mulching films to replace non-degradable mulching films; while mulching mulching film is beneficial to the growth of crops, the breeding of weeds is also serious, so manual weeding or herbicides are required, and the labor cost is high; herbicide mulching films are The new chemical weeding methods developed in recent years have played a certain role in reducing labor costs, reducing the toxicity of pesticides to the human body and environmental pollution.

The currently used herbicide mulch film is made into film by spraying, smearing, etc., and some is modified and granulated by blending the herbicide in the raw material, but applying the herbicide will waste a lot of manpower and material resources; there are also many in this regard. Patents, such as the patent with the application number of 201210525950.7, is a completely biodegradable weeding film, which is composed of PBAT, PBAT+PLA or PBAT+PPC and herbicides, chain extenders, and mold release agents. PBAT, PBAT are mixed with a mixer. +PPC or PBAT+PLA and herbicides, chain extenders, and mold release agents are mixed evenly, and then the blended materials are extruded, modified and pelletized with a twin-screw extruder; the patent application number is 95108803.3, a A light-controllable and biodegradable weeding agricultural mulch film, the components of which comprise 50-70 parts of polyethylene resin, 30-50 parts of modified starch, 0.02-0.30 parts of photosensitizer, 0.01-0.08 parts of pro-oxidant, and 0.02 part of degradation control agent. -0.30 part, herbicide 0.08-0.2 part. The film is added with herbicides, so that the degradable mulch film has the effect of controlling weeds in the process of degradation; the patent application number 201510563522.7 is a fully biodegradable mulch film that can degrade insects and weeds in crops with the following components Composition, polyalkylene alkanoate 70-79%, polylactic acid 8-25%, nano calcium powder 1-4%, chlorantraniliprole 0.05-0.25%, paraquat 0.05-0.25%, carbendazim 0.1-0.5 %, and a biodegradation agent, mixed, kneaded at high speed, and then blown into a film; the patent application number 201610985359.8, the application of a biodegradable weeding film in potato cultivation, consists of the following components, biodegradable resin 70-97% , 3-30% biodegradable herbicide masterbatch, the masterbatch is composed of 10-60% herbicide and 0.5-7% sorbitol laurate and propylene glycol fatty acid ester, and is ultrasonically treated, but it does not prevent weeding Agent precipitation loss. A comprehensive analysis of the above patents shows that herbicides are directly added to plastics or made into herbicide masterbatches and then added to plastics for extrusion blowing. As we all know, if the compatibility between the herbicide and the blended plastic is excellent, then the herbicide will not be precipitated in the plastic, and the purpose of weeding will not be achieved; the herbicide and the blended plastic must be incompatible, and in the process of rain and sunlight exposure The herbicide precipitation can achieve the weeding effect; however, the herbicide that is incompatible with the plastic is very easy to precipitate out when added to the plastic, often the weeds have not yet grown, the precipitation of the herbicide has been completed or there is not much left, even in the process of plastic film storage and transportation A large amount of mulch has been precipitated, so that the concentration of herbicides in the mulch film is greatly reduced, and the herbicidal effect cannot be achieved.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention utilizes the adsorption function of carbon black, mixes herbicides into carbon black, mixes with high-speed stirring, and then under the action of biodegradable resin carrier, granules to make carbon black masterbatch, and then adds in proportion. Blow the film into the degraded mulch material; because the herbicide enters the inner void of the carbon black during the mixing process and is wrapped by the carbon black, the herbicide does not precipitate when the mulch is blown.

The technical scheme of the present invention is as follows: a mulch film for inhibiting the growth of weeds, the mulch film is made of the following components in weight fraction: 100 parts of polylactic acid, polyadipate/butylene terephthalate (PBAT) 50-70 parts, acetyl ethyl citrate, 5-10 parts, antioxidant 0.1-1 part, anti-ultraviolet auxiliary agent 0.5-3 parts, carbon black masterbatch 5-10 parts.

The polylactic acid is levorotatory or racemic polylactic acid, the number average molecular weight is between 30,000 and 150,000, the molecular weight distribution is 1-2, and the crystallinity is 20-60%.

The PBAT is a copolymer of butylene adipate and butylene terephthalate, which has the characteristics of both PBA and PBT, the density is 1.10～1.30 g/cm ³ , and the glass transition temperature is -25～ -35℃, melting point is 110-120℃, produced by BASF.

The acetyl ethyl citrate is acetylated on the basis of ethyl citrate, thereby increasing its binding force with the base resin, reducing the precipitation of the plasticizer, and improving the flexibility and processing performance of the material.

Among them, the antioxidants are preferably 2,6-di-tert-butyl-4-methylphenol and 2,4,6-tri[2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-4- Methyl-6-tert-butylphenolyl]-cyanurate compound, the weight ratio is 1:(0.5-1).

Described anti-ultraviolet auxiliary agent is light stabilizer UV-3853 S and light stabilizer Tinuvin 119 compound, the weight ratio is 1:1, described light stabilizer UV-3853 S is C _12-21 and C ₁₈ unsaturated fatty acid -2,2,6,6-Tetramethyl-4-piperidine ester, which has excellent light stabilization effect; the light stabilizer Tinuvin 119 is a high relative molecular weight triazine-piperidine condensate, and its unique molecular structure enables It has anti-acid properties; low volatility, anti-migration.

Wherein the carbon black masterbatch is made of the following components in terms of weight fraction: polycaprolactone (PCL): 40-60 parts; carbon black: 10-20 parts; herbicide: 10-20 parts; carbon black Dispersant: 1-10 parts; citrate 5-10 parts.

The polycaprolactone (PCL) is a biodegradable polyester with a molecular weight of 1000-3000. The low molecular weight polycaprolactone (PCL) has good processing fluidity and is used for the master batch carrier resin.

The carbon black is M717 carbon black produced by Cabot, and the carbon black has good blackness, easy dispersion and good adsorption properties.

The herbicide is 4,6-bis(isopropylamino)-2-methylthio-1,3,5-triazine or 2-methyl-4-chlorophenoxyacetic acid.

The carbon black dispersion treatment agent is a composite monoalkoxy titanate of the NDZ-131 brand.

The citrate is butyl citrate, which is a biodegradable plasticizer, and the addition of the citrate is beneficial to the uniform mixing of carbon black and polycaprolactone.

The preparation method of a fully biodegradable plastic film for inhibiting weeds of the present invention is:

(1) Preparation of herbicide solution: Mix and stir with acetone or ethanol solvent and herbicide at a ratio of 1-1.5:1, and configure the herbicide into acetone or ethanol solution;

(2) Weigh carbon black, herbicide solution (according to the actual dosage of herbicide converted into solution ratio), carbon black dispersion treatment agent, butyl citrate, polycaprolactone in proportion, and put them into a high-speed mixer together Mixing in medium and heating to 50-70°C to ensure full volatilization of acetone or ethanol; high-speed mixer adopts stepless variable speed mixing, combining fast and slow, slow stirring at 450-600 rpm, and high-speed stirring at 1200-1500 rpm /minute. It is conducive to the rapid adsorption and coating of herbicides by carbon black, and the mixing time is 5-10 minutes, and the mixed material is released;

(3) Weigh PLA, PBAT, acetyl ethyl citrate, antioxidant, anti-ultraviolet additive and mixed carbon black masterbatch in proportion, put them into a high-speed mixer and mix for 5 minutes, and discharge the materials;

(4) Extrude and granulate the mixed material in a twin-screw extruder, the extrusion granulation temperature is 110-170 ℃, and cut into pellets by a plastic pelletizer;

(5) Blowing the formed pellets on a film blowing machine at a temperature of 170-195° C. to a film thickness of more than 6 μm to obtain the weed-inhibiting mulch film of the present invention.

The beneficial effects of the present invention are as follows: in the degradable mulch film, the herbicide is mixed in the carbon black, and the adsorption effect of the carbon black is used to fully adsorb the herbicide in the inner space of the carbon black. It is made into carbon black masterbatch, and then added to biodegradable resin to blow mulch; the advantage of this mulch is that during storage and transportation, the herbicide will not be lost due to the adsorption and coating of the internal voids of carbon black, but it is used in mulch. During the process, under the action of light and heat, the herbicide will be slowly precipitated, and the water droplets formed by the evaporation of surface water on the surface of the mulch film will flow to the surface of the land, thereby playing a role in weeding; especially with the strong sunlight at noon. Direct sunlight, the more herbicides will be precipitated, which has an excellent effect on killing weeds, and the degradable plastic film can be completely biodegraded into carbon dioxide and water, and will not pollute the soil and the environment.

Detailed ways

The present invention is further described below in conjunction with the examples, but does not limit the present invention accordingly.

The trade mark of PLA polylactic acid in the embodiment is trade mark Revode110, Zhejiang Hisun Biomaterials Co., Ltd., density 1.25±0.05, melting point 140-155 ℃; The trade mark and index of PBAT are as follows: trade mark TH801T, Dongguan Renju Biodegradation Plastic Co., Ltd., melting point 110-120℃, density 1.2-1.28g/cm ³ .

The antioxidants are 2,6-di-tert-butyl-4-methylphenol and 2,4,6-tris[2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-4-methylphenol Base-6-tert-butylphenolyl]-cyanurate compound, the weight ratio is 1:1.

The molecular weight of PCL is 2000; the carbon black is M717 carbon black produced by Cabot, and the herbicide is 4,6-bis(isopropylamino)-2-methylthio-1,3,5- Triazine; carbon black dispersant is a composite monoalkoxy titanate, the brand name is NDZ-131.

The carbon black masterbatch is made of the following components in parts by weight: polycaprolactone (PCL): 40 parts; carbon black: 20 parts; herbicide: 20 parts; carbon black dispersion treatment agent: 10 parts; citric acid Butyl ester: 10 parts.

The anti-ultraviolet auxiliary agent is compounded by light stabilizer UV-3853 S and light stabilizer Tinuvin 119, and the weight ratio is 1:1.

Table 1 is the formula of Examples 1-6 of the present invention, and the table is the formula of Examples 7-9 and Comparative Examples 1-3 of the present invention.

Table 1 Examples 1-6 formulas of the present invention, kg

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Table 2 Formulas of Examples 7-9 of the present invention and Comparative Examples 1-3, kg

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In Comparative Example 1, the amount of carbon black masterbatch was reduced on the basis of Example 9, the amount of carbon black masterbatch in Comparative Example 2 was increased on the basis of Example 9, and the carbon black masterbatch adopted in Comparative Example 3 did not add carbon. Black dispersion treatment agent.

Embodiment The preparation method of the fully biodegradable plastic film for suppressing weeds is:

(1) Preparation of herbicide solution: Mix and stir with acetone or ethanol solvent and herbicide at a ratio of 1.5:1, and configure the herbicide into an ethanol solution;

(2) Weigh carbon black, herbicide solution (according to the actual dosage of herbicide converted into solution ratio), carbon black dispersion treatment agent, butyl citrate, polycaprolactone in proportion, and put them into a high-speed mixer together Mixing in medium and heating to 60°C to ensure full volatilization of acetone or ethanol; high-speed mixer adopts stepless variable speed mixing, combining speed and slow, slow stirring at 450-600 rpm, and high-speed stirring at 1200-1500 rpm . It is conducive to the rapid adsorption and coating of herbicides by carbon black, and the mixing time is 10 minutes, and the mixed material is released;

(3) Weigh PLA, PBAT, acetyl ethyl citrate, antioxidant, anti-ultraviolet additive and mixed carbon black masterbatch in proportion, put them into a high-speed mixer and mix for 5 minutes, and discharge the materials;

(4) Extrude and granulate the mixed material in a twin-screw extruder, the extrusion granulation temperature is 110-170 ℃, and cut into pellets by a plastic pelletizer;

(5) Blowing the formed pellets on a film blowing machine at 170-195°C with a film thickness of 8 μm to obtain a weed-inhibiting mulch film.

The performance test results of Examples and Comparative Examples are shown in Table 3.

table 3

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Table 4 shows the test results of the precipitation performance of the mulch films of the examples and comparative examples under certain conditions.

Table 4 Test results of precipitation performance of degradable plastic film examples and comparative examples

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Test conditions: Put a certain weight of mulch sample into a solution of 3% detergent concentration, soak it at room temperature for 168 hours, then take it out and place it to dry at room temperature for 48 hours, weigh and calculate the weight loss of the mulch, expressed as a percentage, the higher the value. A low value indicates that the precipitation is more difficult, and vice versa, the precipitation is more serious.

It can be seen from the performance test results that the anti-extraction herbicide ability of the mulch film blown by the biodegradable mulch masterbatch of the present invention is better than that of the comparative example.

Through the test of planting peanuts, the pesticide in the mulch film of the present invention is slow-release and has a long drug effect time. Under the same planting conditions, the peanut yield of Example 9 is 18% higher than that of Comparative Example 1, and 12% higher than that of Comparative Example 2. 3 is 10% higher.

Claims (6)

1. A mulching film for inhibiting weed growth is prepared from the following components in parts by weight: 100 parts of polylactic acid, 50-70 parts of poly (butylene adipate)/terephthalate, 5-10 parts of acetyl ethyl citrate, 0.1-1 part of antioxidant, 0.5-3 parts of anti-ultraviolet auxiliary agent and 5-10 parts of carbon black master batch;

the carbon black master batch is prepared from the following components in parts by weight: 40-60 parts of polycaprolactone, 10-20 parts of carbon black, 10-20 parts of herbicide, 1-10 parts of carbon black dispersion treatment agent and 5-10 parts of citric acid ester; the carbon black dispersion treatment agent is composite monoalkoxy titanate with the brand of NDZ-131.

2. The mulching film for inhibiting the growth of weeds of claim 1, wherein the polycaprolactone is a biodegradable polyester with a molecular weight of 1000-3000.

3. The mulching film for inhibiting the growth of weeds of claim 1, wherein said carbon black is carbon black of cabot M717.

4. The mulch film for inhibiting the growth of weeds of claim 1 wherein the herbicide is 4, 6-bis (isopropylamino) -2-methylthio-1, 3, 5-triazine or 2-methyl-4-chlorophenoxyacetic acid.

5. The weed growth inhibiting mulch of claim 1, wherein the citrate ester is butyl citrate.

6. A method of preparing a mulching film for suppressing the growth of weeds of claim 1, comprising the steps of, in order:

(1) preparing a herbicide solution: mixing the acetone or ethanol solvent and the herbicide according to the ratio of 1-1.5: 1, mixing and stirring the mixture according to the proportion, and preparing the solid powder herbicide into an acetone or ethanol solution;

(2) weighing carbon black, a herbicide solution, a carbon black dispersion treatment agent, butyl citrate and polycaprolactone in proportion, putting the weighed materials into a high-speed mixer together for mixing treatment, and heating to 50-70 ℃ to ensure that acetone or ethanol is fully volatilized; the high-speed mixer adopts stepless speed change mixing, the speed and the speed are combined, the low-speed stirring speed is 450-; the carbon black is favorable for adsorbing and coating the herbicide quickly, the mixing time is 5-10 minutes, and the mixed material is discharged to obtain a carbon black master batch, wherein the herbicide solution is weighed according to the solution proportion converted from the actual dosage of the herbicide;

(3) weighing PLA, PBAT, ethyl acetylcitrate, antioxidant, anti-ultraviolet auxiliary agent and mixed carbon black master batch in proportion, putting the weighed materials into a high-speed stirrer to mix for 5min, and discharging the materials;

(4) extruding and granulating the mixed materials in a double-screw extruder at the extrusion granulation temperature of 110-170 ℃, and cutting the materials into granules by a plastic granulator;

(5) and blowing the produced granules on a film blowing machine at the temperature of 170-195 ℃ to obtain the mulching film for inhibiting the growth of weeds.