A degradable and long service life grass cloth and a preparation method thereof

Abstract

The application relates to the technical field of grass-proof cloth processing, in particular to a degradable and long-service-life grass-proof cloth and a preparation method thereof, which is prepared from the following raw materials in percentage by weight: 50-70% of polylactic acid, 1-3% of a modifier, 0.5-1% of a plasticizer, 2-5% of a monoacylglyceride, 5-10% of starch, and the rest of porous fillers, wherein the modifier is obtained by mixing fatty acid polyoxyethylene ester, sulfonated lignin salt and hydroxyethyl methacrylate. The grass-proof cloth prepared through the above-mentioned formula has excellent degradability, strong mechanical properties and weather resistance, so that the grass-proof cloth can maintain stable performance for a long time, thereby prolonging the service life.

Description

Technical Field

[0001] This application relates to the field of weed control fabric processing technology, and more specifically, to a biodegradable and long-lasting weed control fabric and its preparation method. Background Technology

[0002] Weed control fabric is an environmentally friendly material widely used in agriculture, horticulture, and landscaping projects. Its main function is to effectively suppress weed growth, reduce the use of herbicides, thereby reducing agricultural production costs and protecting the ecological environment.

[0003] Existing weed control fabrics are mainly made of polypropylene, polyethylene, and polylactic acid. Polypropylene and polyethylene weed control fabrics both possess high tensile and tear strength, and exhibit good resistance to environmental factors such as ultraviolet radiation and oxidation, resulting in a long service life. However, both polypropylene and polyethylene weed control fabrics have poor biodegradability, potentially causing environmental pollution after long-term use. To prevent polypropylene and polyethylene weed control fabrics from exacerbating environmental pollution, researchers have begun exploring biodegradable materials for weed control fabrics.

[0004] Polylactic acid (PLA) is a fully biodegradable material that can be completely degraded into carbon dioxide and water by microorganisms in the natural environment, making it environmentally friendly and effectively solving the problem of non-degradability of polypropylene and polyethylene weed control fabrics. However, PLA weed control fabrics have relatively weak heat resistance and are prone to deformation or degradation under direct sunlight and high temperatures. In regions of my country such as Tibet, Xinjiang, Guangdong, and Yunnan, where there is long hours of sunshine, its service life is short, typically 1-2 years, requiring frequent replacement to avoid affecting the weed control effect. Summary of the Invention

[0005] In order to improve the tensile strength and service life of polylactic acid weed control fabric, this application provides a biodegradable weed control fabric with a long service life and a method for preparing the same.

[0006] In a first aspect, this application provides a biodegradable and long-lasting weed control fabric, employing the following technical solution: A biodegradable and long-lasting weed control fabric is prepared from the following raw materials by weight percentage: Polylactic acid 50-70% Modifier 1-3% Plasticizer 0.5-1% Monoacylglycerol 2-5% Starch 5-10% The remainder is porous packing material. The modifier is obtained by mixing fatty acid polyoxyethylene ester, sulfonated lignin salt and hydroxyethyl methacrylate.

[0007] By adopting the above technical solutions, weed control fabric can maintain excellent degradability while also possessing strong mechanical properties and weather resistance, enabling it to maintain stable performance over a longer period of time and thus extending its service life.

[0008] Starch acts as a physical cross-linker in weed control fabric, increasing its density and tensile strength, thus improving its durability. The addition of porous fillers enhances the overall stiffness and resistance to deformation. This combined effect allows the weed control fabric to maintain good morphological stability under external tensile forces, extending its service life. Furthermore, starch is biodegradable, which helps improve the degradation performance of the weed control fabric. In addition, porous fillers are used to adjust the material's density and water absorption, improving its air and water permeability. Monoacylglycerols, as natural oil derivatives, facilitate the uniform dispersion of components during mixing, improving the overall performance of the weed control fabric and promoting the degradation process of PLA, thus increasing the material's biodegradation rate.

[0009] The main function of modifiers is to increase the flexibility and impact resistance of polylactic acid (PLA), preventing brittleness during use and extending the service life of weed control fabric. Fatty acid polyoxyethylene esters can improve the surface wettability and permeability of PLA, promoting the uniform mixing and processing of PLA, starch, and porous fillers. The sulfonic acid groups in sulfonated lignin salts can participate in the curing reaction of PLA, forming stable chemical bonds, thereby enhancing the material's cohesion and crack resistance. Hydroxyethyl methacrylate can increase the crosslinking density and weather resistance of PLA, contributing to enhanced durability of the weed control fabric. The combined use of these three modifiers significantly improves the impact resistance and durability of the weed control fabric.

[0010] The main function of plasticizers is to increase the softness and plasticity of materials, making them easier to process and shape.

[0011] Preferably, the fatty acid polyoxyethylene ester, the sulfonated lignin salt and the hydroxyethyl methacrylate are mixed in a weight ratio of (1-3):(4-6):5.

[0012] By adopting the above technical solution and optimizing the dosage of fatty acid polyoxyethylene ester, sulfonated lignin salt and hydroxyethyl methacrylate, the toughness of weed control fabric is significantly improved, making it less prone to breakage or damage during use.

[0013] Preferably, the porous packing is a modified porous packing, prepared by the following method: 1) Mix the porous packing with sodium hydroxide solution, heat to 60-70℃ and stir, then filter to obtain hydroxylated porous packing; 2) Mix N-hydroxymethylacrylamide, vinyltrimethoxysilane, trimethylolethane and solvent, add hydroxylated porous packing, heat to 60-70℃, reflux, let stand to room temperature, filter, wash and dry to obtain modified porous packing.

[0014] Porous fillers have poor compatibility with polylactic acid (PLA) and starch, making them difficult to mix evenly. The porous filler prepared using the above method combines more stably with PLA and starch, resulting in a longer service life for weed control fabric.

[0015] In step 1), the porous filler is surface-treated in an alkaline environment with sodium hydroxide to introduce hydroxyl functional groups, increasing the reactivity of the porous filler surface and providing more binding sites for subsequent reactions. In step 2), the hydroxymethyl and amide groups of N-hydroxymethylacrylamide can react with the hydroxyl groups on the surface of the porous filler to form stable chemical bonds, thereby enhancing the overall structure and stability of the porous filler. The silane groups of vinyltrimethoxysilane can undergo a condensation reaction with the hydroxyl groups on the surface of the porous filler to form silicon-oxygen bonds, further increasing the stability and weather resistance of the filler. Trimethylolethane, as a polyol, can provide more hydroxyl groups and work together with N-hydroxymethylacrylamide and vinyltrimethoxysilane to enhance the crosslinking degree of the filler. The modified porous filler has significantly improved compatibility with polylactic acid and starch, forming a more uniform composite material in weed control fabric, which is beneficial for enhancing the overall stiffness and deformation resistance of the weed control fabric, improving its stability, and extending its service life.

[0016] Preferably, the raw materials used to prepare the modified porous filler are in the following weight proportions: 30-35 parts of porous packing 40-50 parts of sodium hydroxide solution 3-6 parts of N-hydroxymethylacrylamide Vinyltrimethoxysilane 4-8 parts 10-15 parts of trimethylolethane 30-40 parts solvent.

[0017] By adopting the above technical solution, optimizing the weight of raw materials used in the modified porous filler, and introducing appropriate amounts of organic functional groups such as N-hydroxymethylacrylamide and vinyltrimethoxysilane, the compatibility of the modified porous filler with polymers such as polylactic acid is improved, which helps to form a more uniform composite material in weed control fabric.

[0018] Preferably, the average particle size of the porous filler is 0.1-1 micrometer.

[0019] By adopting the above technical solution, the average particle size of the porous filler allows the porous filler particles to form a denser filling structure in polylactic acid, thereby improving the mechanical strength of the weed control fabric, such as tensile strength and tear strength.

[0020] Preferably, the porous filler is obtained by mixing aluminosilicate, alumina ceramic and silicon carbide ceramic in a weight ratio of (2-3):(4-6):5.

[0021] Alumina ceramics possess high hardness and strength, significantly improving the tensile and tear strength of weed control fabric. Silicon carbide ceramics exhibit excellent wear resistance, increasing the surface abrasion resistance of the weed control fabric and extending its service life. The addition of aluminosilicates may help improve the dispersibility of fillers and their compatibility with the polymer matrix, thereby further enhancing the overall physical properties of the weed control fabric. Furthermore, by adjusting the ratio of aluminosilicates, alumina ceramics, and silicon carbide ceramics, the degradation rate of the weed control fabric can be controlled to some extent.

[0022] Preferably, the starch is pretreated, and the pretreatment steps are as follows: Water and starch are mixed and heated to 55-60℃. Amylase is added to react, followed by the addition of castor oil polyol and maleic anhydride. The mixture is then heated to 90-100℃ to react and obtain pretreated starch.

[0023] By adopting the above technical solution, the molecular structure and morphology of the pretreated starch have changed, which allows the modified starch to form a more stable network structure in the weed control fabric. This helps to improve the mechanical strength, abrasion resistance and tear resistance of the weed control fabric, thereby extending its service life, while not affecting its degradation.

[0024] Amylase has high activity and can effectively catalyze the decomposition of starch, altering the crystalline structure of starch granules and forming more pores and channels. Castor oil polyol is a compound containing multiple hydroxyl groups, which can undergo esterification with maleic anhydride to generate a polyester with a cross-linked structure. Simultaneously, since starch molecules also contain hydroxyl groups, they participate in the esterification reaction, forming a cross-linked network together with castor oil polyol and maleic anhydride. This cross-linked network structure gives the pretreated starch better mechanical properties and stability.

[0025] Preferably, the weight ratio of the starch, the amylase, the castor oil polyol and the maleic anhydride is (10-15):(0.2-0.5):(1-3):4.

[0026] By adopting the above technical solution, the dosage of starch, amylase, castor oil polyol and maleic anhydride is optimized, so that starch, castor oil polyol and maleic anhydride react fully and reduce the generation of impurities.

[0027] Secondly, this application provides a method for preparing a biodegradable and long-lasting weed control fabric, employing the following technical solution: A method for preparing a biodegradable and long-lasting weed control fabric includes the following preparation steps: S1. Mix polylactic acid, modifier, plasticizer, monoacylglycerol ester, starch and porous filler to obtain a mixture; S2. The mixture is melt-spun into fibers, and the fibers are woven or knitted to form weed control fabric.

[0028] Preferably, the residence time of the mixture in the single screw of the melt spinning machine is 4-6 minutes, and the melt spinning temperature is 200-235℃.

[0029] By adopting the above technical solution, the raw materials can be fully mixed to form uniform fibers, which are then woven into weed control fabric, resulting in a weed control fabric with good degradability and durability.

[0030] In summary, this application has the following beneficial effects: 1. Biodegradability: Since the main raw materials are PLA and starch and other biodegradable materials, the weed control fabric can be quickly decomposed by the natural environment after being discarded, and will not cause long-term pollution.

[0031] 1. Long service life: By adding modifiers such as fatty acid polyoxyethylene ester, sulfonated lignin salt and hydroxyethyl methacrylate, plasticizer and monoacylglycerol ester, the toughness and processing performance of PLA are significantly improved, so that weed control fabric has a longer service life during use.

[0032] 2. Excellent mechanical properties: Through the combined action of polylactic acid, modifiers, plasticizers, monoacylglycerol esters, starch and porous fillers, weed control fabric has good impact resistance, tensile strength and bending resistance, which enables the weed control fabric to maintain good shape stability when subjected to external tensile force and extend its service life. Detailed Implementation Example

[0033] Example 1 A biodegradable and long-lasting weed control fabric is prepared by the following method: S1. Mix 500g of polylactic acid, 30g of modifier, 5g of plasticizer (dioctyl adipate), 20g of monoacylglycerol ester, 50g of starch and 395g of porous filler (aluminosilicate) to obtain a mixture; S2. The mixture is melt-spun into fibers, and the fibers are woven or knitted to form weed control fabric.

[0034] The residence time of the mixture in the single screw of the melt spinning machine is 4 minutes, and the melt spinning temperature is 200℃.

[0035] The starch is corn starch.

[0036] The difference between Examples 2-3 and Example 1 lies in the types and amounts of some raw materials used in the preparation of the weed control fabric, as well as the experimental parameters. Specific differences are shown in Table 1. Table 1. Raw material types, dosages, and experimental parameters of weed control fabrics in Examples 1-3 Example 4 A biodegradable and long-lasting weed control fabric is provided in this embodiment, which differs from Embodiment 3 in that the fatty acid polyoxyethylene ester, sulfonated lignin salt and hydroxyethyl methacrylate are mixed in a weight ratio of 5:5:5.

[0037] Example 5 A biodegradable and long-lasting weed control fabric, the difference between this embodiment and Embodiment 3 is that the porous filler is a modified porous filler, prepared by the following method: 1) Mix 300g of porous packing with 400g of sodium hydroxide solution (mass fraction of 10%), heat to 60℃ and stir, filter to obtain hydroxylated porous packing; 2) Mix 30g of N-hydroxymethylacrylamide, 40g of vinyltrimethoxysilane, 100g of trimethylolethane and 300g of solvent (ethanol), add hydroxylated porous packing, heat to 60℃, reflux, let stand to room temperature, filter, wash and dry to obtain modified porous packing.

[0038] Example 6 A biodegradable and long-lasting weed control fabric, the difference between this embodiment and Embodiment 3 is that the porous filler is a modified porous filler, prepared by the following method: 1) Mix 350g of porous packing with 500g of sodium hydroxide solution (mass fraction of 10%), heat to 70℃ and stir, filter to obtain hydroxylated porous packing; 2) Mix 60g of N-hydroxymethylacrylamide, 80g of vinyltrimethoxysilane, 150g of trimethylolethane and 400g of solvent (ethanol), add hydroxylated porous packing, heat to 70℃, reflux, let stand to room temperature, filter, wash and dry to obtain modified porous packing.

[0039] Example 7 A biodegradable and long-lasting weed control fabric is described in this embodiment, which differs from Embodiment 3 in that the porous filler is obtained by mixing aluminosilicate, alumina ceramic and silicon carbide ceramic in a weight ratio of 2:4:5.

[0040] Example 8 A biodegradable and long-lasting weed control fabric is described in this embodiment, which differs from Embodiment 5 in that the porous filler is obtained by mixing aluminosilicate, alumina ceramic and silicon carbide ceramic in a weight ratio of 3:6:5.

[0041] Example 9 A biodegradable and long-lasting weed control fabric. The difference between this embodiment and Embodiment 3 is that the starch is pretreated. The pretreatment steps are as follows: Mix 200g of water and 100g of starch, heat to 55℃, add 2g of amylase to react, then add 10g of castor oil polyol and 40g of maleic anhydride, heat to 90-100℃ to react, and obtain pretreated starch.

[0042] The amylase is α-amylase.

[0043] Example 10 A biodegradable and long-lasting weed control fabric. The difference between this embodiment and Embodiment 8 is that the starch is pretreated. The pretreatment steps are as follows: Mix 250g of water and 150g of starch, heat to 60℃, add 5g of amylase to react, then add 30g of castor oil polyol and 40g of maleic anhydride, heat to 90-100℃ to react, and obtain pretreated starch.

[0044] The amylase is α-amylase.

[0045] Example 11 A biodegradable and long-lasting weed control fabric is described in this embodiment, which differs from Embodiment 3 in that the plasticizer is obtained by mixing epoxidized soybean oil and acetylated monoglycerides in a weight ratio of 1:5.

[0046] Example 12 A biodegradable and long-lasting weed control fabric, the difference between this embodiment and Example 10 is that the plasticizer is obtained by mixing epoxidized soybean oil and acetylated monoglycerides in a weight ratio of 3:5.

[0047] Comparative Example Comparative Example 1 A biodegradable and long-lasting weed control fabric is described in this embodiment, which differs from Embodiment 3 in that talc is used instead of fatty acid polyoxyethylene ester.

[0048] Comparative Example 2 A biodegradable and long-lasting weed control fabric is described in this embodiment, which differs from Embodiment 3 in that talc is used instead of sulfonated lignin salt.

[0049] Comparative Example 3 A biodegradable and long-lasting weed control fabric is described in this embodiment, which differs from Embodiment 3 in that talc is used instead of hydroxyethyl methacrylate.

[0050] Comparative Example 4 A biodegradable and long-lasting weed control fabric, the difference between this embodiment and Embodiment 3 is that stearic acid is used instead of monoacylglycerol ester.

[0051] Comparative Example 5 A biodegradable and long-lasting weed control fabric is described in this embodiment, which differs from Embodiment 3 in that polyvinyl alcohol is used instead of starch.

[0052] The molecular weight of polyvinyl alcohol is 5000.

[0053] Comparative Example 6 A biodegradable and long-lasting weed control fabric is described in this embodiment, which differs from Embodiment 3 in that hollow microglass beads are used instead of porous fillers.

[0054] Performance testing The degradable and long-life weed control fabrics of Examples 1-12 and Comparative Examples 1-6 were tested for tensile strength, aging rate and degradability.

[0055] Detection methods / test methods The thickness and basis weight of the weed control fabric in Examples 1-12 and Comparative Examples 1-6 were all the same.

[0056] Breaking strength: The breaking strength (kN) of the weed control fabrics prepared in the above examples and comparative examples was tested according to GB / T 3923.1-2013 Textiles - Tensile properties of fabrics - Part 1: Determination of breaking strength and elongation at break (strip method). Aging rate: The weather resistance of the weed control fabrics prepared in the above examples and comparative examples was tested according to AATCC-169-2003 "Textiles Weather Resistance Test: Xenon Arc Lamp Exposure". The tensile strength (N) of the weed control fabrics before and after exposure was recorded, and the aging rate of the tensile strength of the weed control fabrics before and after exposure was calculated.

[0057] Degradability Test: The biodegradable and long-lasting weed control fabrics prepared in Examples 1-12 and Comparative Examples 1-6 were cut into 10cm*10cm samples, buried in soil, and the degree of degradation was observed after 4 months. No visible debris indicated complete degradation; the presence of debris indicated degradation to the point of debris; a rotten area exceeding 80% indicated large-area rot; a rotten area between 50-80% indicated medium-area rot; a rotten area between 30-50% indicated small-area rot; and a rotten area less than 30% indicated no degradation. Experimental data are shown in Table 2. Table 2. Fracture strength test data of Examples 1-12 and Comparative Examples 1-6 Comparing Example 3 and Comparative Examples 1-3, the tensile strength of Comparative Examples 1-3 before the aging test was significantly lower than that of Example 3, and the aging rate of Comparative Examples 1-3 was significantly higher than that of Example 3. During the degradation test, Comparative Examples 1-3 showed medium-area decay, and the degradation effect was lower than that of Example 3. This indicates that by using fatty acid polyoxyethylene ester, sulfonated lignin salt and hydroxyethyl methacrylate together, this application can improve the tensile strength and aging resistance of the weed control fabric, and at the same time improve the degradation performance of the weed control fabric.

[0058] Comparing Example 3 with Comparative Examples 4-5, the tensile strength of Comparative Examples 4-5 before the aging test was less than that of Example 3, and the aging rate of Comparative Examples 4-5 was significantly greater than that of Example 1. During the degradation test, Comparative Examples 4-5 showed only a small area of ​​decay, and the degradation effect was lower than that of Example 3. This indicates that by using hydroxyethyl methacrylate, starch and other raw materials together, it is beneficial to improve the tensile strength and aging resistance of the weed control fabric, and at the same time, it can also improve the degradation performance of the weed control fabric.

[0059] Compared with Comparative Example 6, although the tensile strength and aging rate of Comparative Example 6 were improved, the degradation ability of Comparative Example 6 was significantly reduced, indicating that the degradation performance of weed control fabric can be further improved by using porous fillers.

[0060] Compared with Example 4, Example 6 showed a slight decrease in tensile strength and aging rate, indicating that adjusting the ratio of fatty acid polyoxyethylene ester, sulfonated lignin salt, and hydroxyethyl methacrylate can improve the tensile strength and aging resistance of weed control fabric.

[0061] Comparing Examples 3 and 5-6, the tensile strength of Examples 5-6 before the aging test was significantly higher than that of Example 3, and the aging rate of Examples 5-6 was significantly lower than that of Example 3. During the degradation test, Examples 5-6 were completely degraded, and the degradation effect was better than that of Example 3. This indicates that the modified porous filler prepared by this application can further improve the tensile strength and aging resistance of weed control fabric, and also improve the degradation performance of weed control fabric.

[0062] Compared with Example 7, Example 7 showed a slight increase in tensile strength and aging rate; during the degradation test, Example 7 was degraded to fragments, and the degradation effect was better than that of Example 3. Compared with Example 8, Example 8 showed a slight increase in fracture strength and aging rate. As can be seen from Examples 3 and 7, 5 and 8, by using a mixture of aluminosilicate, alumina ceramic and silicon carbide ceramic, the tensile strength and aging resistance of weed control fabric can be further improved, and the degradation performance of weed control fabric can also be improved.

[0063] Compared with Example 9, Example 9 showed a slight increase in tensile strength and aging rate; Example 9 was completely degraded during the degradation test, and the degradation effect was better than that of Example 3. Compared with Example 10, Example 8 shows a slight increase in fracture strength and aging rate. As can be seen from Examples 3 and 9, 8 and 10, pretreatment of starch can further improve the tensile strength and aging resistance of weed control fabric, and also improve the degradation performance of weed control fabric.

[0064] Compared with Example 11, Example 3 shows a slight increase in fracture strength and aging rate. Compared with Example 12, Example 10 shows a slight increase in fracture strength and aging rate. As can be seen from Examples 3 and 11, 10 and 12, by using epoxidized soybean oil and acetylated monoglycerides in combination, the tensile strength and aging resistance of weed control fabric can be further improved, and its service life can be extended.

[0065] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A biodegradable and long-lasting weed control fabric, characterized in that, It is prepared from the following raw materials by weight percentage: Polylactic acid 50-70% Modifier 1-3% Plasticizer 0.5-1% Monoacylglycerol 2-5% Starch 5-10% The remainder is porous packing material. The modifier is obtained by mixing fatty acid polyoxyethylene ester, sulfonated lignin salt and hydroxyethyl methacrylate; The porous packing is a modified porous packing, prepared by the following method: 1) Mix the porous packing with sodium hydroxide solution, heat to 60-70℃ and stir, then filter to obtain hydroxylated porous packing; 2) Mix N-hydroxymethylacrylamide, vinyltrimethoxysilane, trimethylolethane and solvent, add hydroxylated porous packing, heat to 60-70℃, reflux, let stand to room temperature, filter, wash and dry to obtain modified porous packing; The weight parts of the raw materials used to prepare the modified porous packing are as follows: 30-35 parts of porous packing 40-50 parts of sodium hydroxide solution 3-6 parts of hydroxymethylacrylamide Vinyltrimethoxysilane 4-8 parts 10-15 parts of trimethylolethane 30-40 parts solvent.

2. The biodegradable and long-lasting weed control fabric according to claim 1, characterized in that: The fatty acid polyoxyethylene ester, the sulfonated lignin salt, and the hydroxyethyl methacrylate are mixed in a weight ratio of (1-3):(4-6):

5.

3. The biodegradable and long-lasting weed control fabric according to claim 1, characterized in that: The average particle size of the porous filler is 0.1-1 micrometer.

4. The biodegradable and long-lasting weed control fabric according to claim 1, characterized in that: The porous filler is obtained by mixing aluminosilicate, alumina ceramic and silicon carbide ceramic in a weight ratio of (2-3):(4-6):

5.

5. The biodegradable and long-lasting weed control fabric according to claim 1, characterized in that, The starch is pretreated, and the pretreatment steps are as follows: Water and starch are mixed and heated to 55-60℃. Amylase is added to react, followed by the addition of castor oil polyol and maleic anhydride. The mixture is then heated to 90-100℃ to react and obtain pretreated starch.

6. The biodegradable and long-lasting weed control fabric according to claim 5, characterized in that: The weight ratio of the starch, the amylase, the castor oil polyol, and the maleic anhydride is (10-15):(0.2-0.5):(1-3):

4.

7. The biodegradable and long-lasting weed control fabric according to claim 1, characterized in that: The plasticizer is obtained by mixing epoxidized soybean oil and acetylated monoglycerides in a weight ratio of (1-3):

5.

8. A method for preparing a biodegradable and long-lasting weed control fabric as described in any one of claims 1-7, characterized in that, The preparation steps include the following: S1. Mix polylactic acid, modifier, plasticizer, monoacylglycerol ester, starch and porous filler to obtain a mixture; S2. The mixture is melt-spun into fibers, and the fibers are woven or knitted to form weed control fabric.

Images