Liquid ground film material and preparation method thereof

Abstract

The present invention provides a kind of liquid ground film material and preparation method thereof, the liquid ground film material is made up of tamarind benzoate polysaccharide, modification aid and water, wherein, the mass percentage of the tamarind benzoate polysaccharide is 1 3%, and the mass percentage of the modification aid is 2.3 8.7%.The present invention is by benzoic acid tamarind polysaccharide ester obtained by esterification modification of tamarind polysaccharide with benzoic anhydride as matrix component, can effectively improve the mist and anti-ultraviolet of liquid ground film material, compared to simple tamarind polysaccharide, can also improve mechanical properties.The liquid ground film material provided by the present invention is low in cost, takes into account good mechanical properties, high mist and ultraviolet shielding effect, is conducive to realizing the high value utilization of biomass material, is an extension of functionalized ground film, has greater practical application value and economic benefit.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass utilization and agricultural production, and in particular to a liquid ground film material and a preparation method thereof. Background Art

[0002] Liquid mulch films, when sprayed, form a film on the soil surface, promoting the formation of a granular structure, rather than laying prefabricated films. They stabilize the soil surface and protect the tillage layer. Degradable liquid mulch films not only increase warmth and retain moisture, but also naturally degrade without causing secondary environmental pollution. They significantly reduce water evaporation and increase soil nutrients. The emergence and application of liquid mulch films have significantly boosted agricultural yields and profitability, while also contributing to addressing environmental issues.

[0003] Tamarind is a large evergreen tree of the genus Tamarindus in the family Suaeda. Its pulp is rich in nutrients and has high edible value and health benefits. However, its byproduct, tamarind seeds, is often treated as waste, causing pollution and waste. Tamarind polysaccharides account for more than 50% of the seeds. They are xyloglucans composed of galactose, xylose, and glucose in a ratio of approximately 1:2:3. They have good film-forming properties, are recyclable, and are environmentally friendly. CN112876793A discloses a composite liquid film agent. The composite liquid film agent is made of tamarind composite powder composed of tamarind kernel powder and carbonized seed coat powder as the main components, and is prepared with a binder, a surfactant, a plasticizer, and water. The composite liquid film agent is significantly superior to ordinary plastic mulch films and is environmentally friendly and degradable.

[0004] However, it shares some common drawbacks with existing liquid mulches: low strength, poor toughness, easy cracking, short lifespan, and a significant decrease in mechanical properties after a period of use. Furthermore, it lacks functionality and cannot adapt to the diverse needs of production and life in the new era. Therefore, research on functional, biodegradable liquid mulches based on natural polysaccharides is particularly important in the current materials field. Summary of the Invention

[0005] The present invention provides a liquid ground film material and a preparation method thereof, which are used to solve the defects of the prior art such as poor mechanical properties of ground films and insufficient ability to alleviate the side effects of light, and achieve performance optimization of the degradable liquid ground film material.

[0006] The invention provides a liquid mulch material, which consists of tamarind polysaccharide benzoate, a modification aid and water. The mass percentage of the tamarind polysaccharide benzoate in the liquid mulch material is 1-3%, and the mass percentage of the modification aid in the liquid mulch material is 2.3-8.7%.

[0007] Haze is the percentage of transmitted light intensity that deviates from the incident light by more than 2.5° to the total transmitted light intensity. It can be used to characterize the cloudy appearance caused by light scattering inside or on the surface of a transparent or translucent sample. Some areas with harsh climates, such as Africa and some desert areas, are not only dry but also accompanied by wind, sand, high temperature, strong light, etc., which seriously affect crop growth. Liquid mulch with haze can soften the light intensity, making the light suitable for plant growth, effectively reducing the surface temperature of leaves, and at the same time facilitating sand aggregation and preventing wind and sand. The attenuation of the ozone layer above the earth and the increase in ultraviolet radiation have a great impact on terrestrial ecosystems and even humans. A large number of studies have shown that the increase in UVB radiation has inhibited the growth of most plants. Anti-ultraviolet mulch can alleviate the side effects of ultraviolet radiation on plants to a certain extent.

[0008] The present invention uses tamarind polysaccharide benzoate as a base component, which can effectively improve the haze and UV resistance of liquid mulch film materials. Compared with pure tamarind polysaccharide, it also improves mechanical properties. This improved overall performance expands the scope of application and has great practical application value and economic benefits.

[0009] According to the liquid mulch material provided by the present invention, the tamarind polysaccharide benzoate is prepared by esterification reaction of benzoic anhydride and tamarind polysaccharide, and the mass ratio of the benzoic anhydride to the tamarind polysaccharide is 1:1 to 4:1.

[0010] Benzoic anhydride itself has a UV shielding effect. Esterification modification of tamarind polysaccharide with it can enhance the UV shielding effect of tamarind polysaccharide. It was also unexpectedly found that the haze was also greatly improved.

[0011] The tamarind polysaccharide of the invention is obtained by water extraction and alcohol precipitation of tamarind kernel powder, and the polysaccharide content is above 82%.

[0012] According to the liquid mulch material provided by the present invention, the preparation of the tamarind polysaccharide benzoate comprises:

[0013] At a temperature of 30-50°C, tamarind polysaccharide is dispersed in N,N-dimethylformamide, 4-dimethylaminopyridine and anhydrous potassium carbonate are added, and activated for 1-3 hours;

[0014] The benzoic anhydride solution is added to the activated tamarind polysaccharide solution and the esterification reaction is carried out for 10 to 12 hours.

[0015] That is, the tamarind polysaccharide must be activated before the esterification reaction, and the activation reagent is a mixture of 4-dimethylaminopyridine and anhydrous potassium carbonate, which has a better effect.

[0016] In some embodiments of the present invention, the mass ratio of N,N-dimethylformamide to tamarind polysaccharide is 50:1 to 20:1; the mass ratio of 4-dimethylaminopyridine to tamarind polysaccharide is 2:1 to 4:1; and the mass ratio of anhydrous potassium carbonate to tamarind polysaccharide is 0.2:1 to 0.5:1.

[0017] In some embodiments of the present invention, the benzoic anhydride solution is obtained by dissolving benzoic anhydride in N,N-dimethylformamide.

[0018] In some embodiments of the present invention, after the esterification reaction is completed, the solvent is filtered off, the reaction is terminated by washing with 95% ethanol, and the product tamarind polysaccharide benzoate is obtained after drying.

[0019] According to the liquid mulch material provided by the present invention, the modification auxiliary agent includes galactomannan and aqueous polyurethane, and the mass ratio of the galactomannan, aqueous polyurethane and tamarind polysaccharide benzoate is 0.5-1.5:0.5-2.5:1-3.

[0020] Galactomannans are widely distributed in nature, primarily obtained from the endosperm of leguminous plant seeds. They exhibit thickening and gelling properties in aqueous media and are widely used in industry and food production as thickeners and stabilizers. The galactomannans used in the present embodiments have a polysaccharide content of at least 75%.

[0021] The present invention adds galactomannan and waterborne polyurethane to enhance the strength and toughness of the polysaccharide film material, wherein the strength increase is more significant, exceeding general expectations. The waterborne polyurethane used in the embodiment of the present invention is an anionic waterborne polyurethane with a solid content of 20-60%.

[0022] According to the liquid ground film material provided by the present invention, the modification auxiliary agent further includes a plasticizer, and the plasticizer is composed of urea, polyvinyl alcohol and glycerol in a mass ratio of 0.5-1.5:0.25-1.5:0.5-1.5.

[0023] In the prior art, propylene glycol or polyvinyl alcohol is used alone as a plasticizer. The present invention has found that for the system of the present invention, compounding urea, polyvinyl alcohol and propylene glycol in a specific ratio as a plasticizer can significantly improve the toughness of the liquid mulch material.

[0024] According to the liquid mulch material provided by the present invention, the modification auxiliary agent also includes saponin. Calculated by mass percentage, the liquid mulch material is composed of: 1-3% tamarind polysaccharide benzoate, 0.5-1.5% galactomannan, 0.5-2.5% water-based polyurethane, 0.5-1.5% urea, 0.25-1.5% polyvinyl alcohol, 0.5-1.5% glycerol, 0.05-0.2% saponin and the balance water.

[0025] Saponins are a class of ingredients with a relatively complex structure, consisting of saponins and sugars, uronic acids, or other organic acids. They are widely found in the plant kingdom, distributed in both monocots and dicots. Saponins are primarily used as pharmaceutical ingredients, serving as a raw material for the production of over twenty steroid hormones, including cortisone, testosterone, progesterone, and oral contraceptives. They are also used in the production of detergents, emulsifiers, foaming agents, and preservatives. The present inventors unexpectedly discovered that the addition of saponins can improve the uniformity of composite blended membrane materials and exhibits excellent antibacterial and bactericidal properties.

[0026] Under the above preferred formula, the raw materials are green and environmentally friendly, low-cost, safe to use, and biodegradable. The prepared liquid mulch film material has certain water resistance, mechanical strength, and thermal insulation and moisture retention properties. It has a high haze, which softens light, making it suitable for plant growth, while also promoting sand aggregation and preventing wind and sand. It also has a UV shielding effect, which can alleviate the side effects of UV radiation on plants to a certain extent, facilitating the high-value utilization of biomass materials.

[0027] The present invention also provides a method for preparing the liquid ground film material.

[0028] The preparation method provided by the invention comprises the following steps: dissolving tamarind polysaccharide benzoate in water at a temperature of 75-90° C., adding galactomannan, aqueous polyurethane, urea, polyvinyl alcohol, glycerol and saponin, blending the mixture, and stirring at a constant temperature for 40-70 minutes.

[0029] The present invention also provides a method for using the liquid ground film material, comprising spraying the liquid ground film material on the soil surface to form a film, wherein the spraying amount of the liquid ground film material is 1 to 2.5 kg / m 2 .

[0030] According to the method for using the liquid ground film material provided by the present invention, after film formation, the liquid ground film has a thickness of 50 to 90 μm, a stress of 10 to 25 MPa, a strain of 50 to 80%, a haze of more than 85%, and blocks more than 95% of ultraviolet rays.

[0031] The present invention provides a liquid mulch film material and a preparation method thereof. Using tamarind polysaccharide benzoate, obtained by esterifying tamarind polysaccharide with benzoic anhydride, as a base component, the material effectively improves its haze and UV resistance. Compared to pure tamarind polysaccharide, it also exhibits improved mechanical properties. This invention facilitates the high-value utilization of biomass materials, expands upon the development of functional mulch films, and possesses significant practical application value and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1This is a schematic diagram of the process for preparing liquid ground film material in an embodiment of the present invention;

[0033] Figure 2 2 are a physical image and a scanning electron micrograph of a film made from the liquid ground film material of Example 2; wherein (a) is a physical image of a film made from the liquid ground film material of Example 2, and (b) is a scanning electron micrograph of a film made from the liquid ground film material of Example 2;

[0034] Figure 3 2 are scanning electron micrographs of sand and a scanning electron micrograph of Example 2 after spraying onto the sand; wherein (a) is a scanning electron micrograph of untreated sand, and (b) is a scanning electron micrograph of Example 2 after spraying onto the sand surface. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] Unless otherwise specified, the raw materials involved in the following examples can be obtained through regular commercial channels. Unless otherwise specified, the percentages involved are by mass.

[0037] Example 1

[0038] This embodiment provides a liquid ground film material, which is composed of the following:

[0039] Tamarind polysaccharide benzoate 1%, galactomannan 0.5%, aqueous polyurethane 0.5%, urea 0.5%, polyvinyl alcohol 0.25%, glycerol 0.5%, saponin 0.05% and the balance water.

[0040] Its preparation process is as follows Figure 1 The specific steps are as follows:

[0041] Step 1: Activation of Tamarind Polysaccharide: 2% tamarind polysaccharide was uniformly dispersed in N,N-dimethylformamide at 30°C. 4% 4-dimethylaminopyridine and 0.4% anhydrous potassium carbonate were added for 1 hour. (The mass percentages in this step are based on the amount of N,N-dimethylformamide used; the same applies to the steps in the remaining examples.)

[0042] Step 2: Benzoic anhydride esterification modification. Dissolve benzoic anhydride in N,N-dimethylformamide and slowly add it to the activated tamarind polysaccharide solution (control the mass ratio of benzoic anhydride to tamarind polysaccharide to be 1:1). The esterification reaction time is 10 hours. After filtering the solvent, wash with 95% ethanol to terminate the reaction. After drying, the product tamarind polysaccharide benzoate is obtained.

[0043] Step 3: Membrane material preparation: Dissolve 1% tamarind polysaccharide benzoate in water at 75°C, add 0.5% galactomannan, 0.5% water-based polyurethane, 0.5% urea, 0.25% polyvinyl alcohol, 0.5% glycerol, and 0.05% saponin for blending and modification, and stir at a constant temperature for 60 minutes to obtain a liquid ground membrane material.

[0044] The liquid ground film material is sprayed to form a film, thereby obtaining a formed ground film.

[0045] Example 2

[0046] This embodiment provides a liquid ground film material, which is composed of the following:

[0047] Tamarind polysaccharide benzoate 2%, galactomannan 1%, aqueous polyurethane 1.5%, urea 1%, polyvinyl alcohol 0.875%, glycerol 1%, saponin 0.125% and the balance water.

[0048] The specific preparation steps are as follows:

[0049] Step 1: Activation of Tamarind Polysaccharide: Disperse 3.5% of Tamarind Polysaccharide evenly in N,N-dimethylformamide at 40°C, add 10.5% of 4-dimethylaminopyridine and 1.2% of anhydrous potassium carbonate, and activate for 2 hours.

[0050] Step 2: Benzoic anhydride esterification modification. Dissolve benzoic anhydride in N,N-dimethylformamide and slowly add it to the activated tamarind polysaccharide solution (control the mass ratio of benzoic anhydride to tamarind polysaccharide to be 2.5:1). The esterification reaction time is 11 hours. After filtering the solvent, wash with 95% ethanol to terminate the reaction. After drying, the product tamarind polysaccharide benzoate is obtained.

[0051] Step 3: Membrane material preparation: Dissolve 2% tamarind polysaccharide benzoate in water at 82.5°C, add 1% galactomannan, 1.5% water-based polyurethane, 1% urea, 0.875% polyvinyl alcohol, 1% glycerol, and 0.125% saponin for blending and modification, and stir at constant temperature for 55 minutes to obtain a liquid ground membrane material.

[0052] The liquid ground film material is sprayed to form a film, thereby obtaining a formed ground film.

[0053] Example 3

[0054] This embodiment provides a liquid ground film material, which is composed of the following:

[0055] 3% tamarind polysaccharide benzoate, 1.5% galactomannan, 2.5% waterborne polyurethane, 1.5% urea, 1.5% polyvinyl alcohol, 1.5% glycerol, 0.2% saponin and the balance water.

[0056] The specific preparation steps are as follows:

[0057] Step 1: Activation treatment of tamarind polysaccharide: 5% tamarind polysaccharide is evenly dispersed in N,N-dimethylformamide at 50°C, and 15% 4-dimethylaminopyridine and 2.5% anhydrous potassium carbonate are added for 3 hours;

[0058] Step 2: Benzoic anhydride esterification modification. Dissolve benzoic anhydride in N,N-dimethylformamide and slowly add it to the activated tamarind polysaccharide solution (control the mass ratio of benzoic anhydride to tamarind polysaccharide to be 4:1). The esterification reaction time is 112 hours. After filtration of the solvent, the reaction is terminated by washing with 95% ethanol. After drying, the product tamarind polysaccharide benzoate is obtained.

[0059] Step 3: Membrane material preparation: Dissolve 3% tamarind polysaccharide benzoate in water at 90°C, add 1.5% galactomannan, 2.5% water-based polyurethane, 1.5% urea, 1.5% polyvinyl alcohol, 1.5% glycerol, and 0.2% saponin, and mix and modify. Stir at constant temperature for 50 minutes to obtain a liquid ground membrane material.

[0060] The liquid ground film material is sprayed to form a film, thereby obtaining a formed ground film.

[0061] Example 4

[0062] This embodiment provides a liquid ground film material, which differs from Example 2 only in that 1% galactomannan and 1.5% aqueous polyurethane are replaced with an equal amount of polyvinyl alcohol.

[0063] Example 5

[0064] This embodiment provides a liquid ground film material, which differs from embodiment 2 only in that 1% urea is replaced with an equal amount of glycerol.

[0065] Comparative Example 1

[0066] This comparative example provides a liquid ground film material, and with reference to patent CN112876793A, its preparation method is as follows:

[0067] At 80°C, 2 g of tamarind seed kernel powder, 0.2 g of carbonized seed coat powder, 0.5 g of polyvinyl alcohol, 0.5 g of camellia saponin, and 0.5 g of glycerol were dissolved in 100 mL of water, stirred evenly, and stirred at a constant temperature for 60 min to obtain a composite liquid film.

[0068] Comparative Example 2

[0069] This comparative example provides a liquid mulch material, and its preparation method is as follows: at a temperature of 82.5°C, 2% tamarind polysaccharide is dissolved in water, 1% galactomannan, 1.5% aqueous polyurethane, 1% urea, 0.875% polyvinyl alcohol, 1% glycerol, and 0.125% saponin are added for blending and modification, and the mixture is stirred at a constant temperature for 55 minutes to obtain a liquid mulch material.

[0070] The performance of the mulch films obtained in each embodiment and comparative example was tested using the following method:

[0071] 10 g of the obtained liquid mulch material was transferred to a 90 mm culture dish, dried at 50° C. for 4 h, peeled off, and equilibrated with temperature and humidity (temperature 23° C. / relative humidity 50%) for 12 h before use in subsequent tests.

[0072] The thickness and mechanical properties of the fully biodegradable agricultural ground covering film were tested with reference to the national standard GB / T35795-2017. The haze and UV resistance tests were carried out with reference to the GB2410-80 test method for light transmittance and haze of transparent plastics. The sand fixation test was carried out by mixing the liquid ground film material of Example 2 with the film at a pressure of 1.5 kg / m 2 The wet spraying amount was sprayed on the surface of sand (90-100 mesh), and the scanning electron micrographs of the untreated sand surface and the sand surface sprayed with liquid mulch were observed respectively.

[0073] The test results are shown in Table 1. The test results of the liquid ground film produced in Examples 1-5 are: thickness of 50-90 μm, stress of 10-25 MPa, strain of 50-80%, haze of more than 85%, and UV blocking of more than 95%. Figure 2 These are the physical pictures and scanning electron micrographs of the membrane made from the liquid ground membrane material of Example 2.

[0074] The test results of the sand fixation test are as follows: Figure 3 As shown, the untreated sand has clear edge contours, loose structure, small contact area, no agglomerates formed, and poor stability; the liquid mulch material of Example 2 is sprayed onto the surface of the sand, and after the water evaporates and dries, a film is formed on the surface of the sand. The sand is bonded together by the liquid mulch material, filling the gaps between the sand and forming a bonding layer on the surface, so that the loose sand is turned into a whole with a certain strength, the arrangement is more compact, and the stability is enhanced, indicating that the liquid mulch material of the present invention has the effect of preventing wind and fixing sand.

[0075] Table 1 Performance parameters of liquid degradable mulch materials

[0076] Thickness (μm) Stress (MPa) strain(%) Haze (%) UV shielding (%) Example 1 54 12.6 56.7 86.3 96.5 Example 2 78 23.3 78.8 87.7 99.1 Example 3 89 24.5 72.9 88.6 99.2 Example 4 61 19.7 69.7 87.2 98.7 Example 5 77 20.9 52.1 87.3 98.3 Comparative Example 1 200 13.9 24.5 63.8 92.7 Comparative Example 2 78 12.4 44.2 72.3 79.2

[0077] The above results demonstrate that tamarind polysaccharide benzoate, obtained by esterifying tamarind polysaccharide with benzoic anhydride as a modifying material, enhances the overall performance of liquid mulch films. This tamarind polysaccharide benzoate improves the haze and UV resistance of the prepared film material, softening and filtering sunlight. Furthermore, the addition of galactomannan, aqueous polyurethane, and urea enhances the strength and toughness of the polysaccharide film material. The mulch films described herein are low-cost, possess excellent mechanical properties, high haze, and UV-shielding properties, and possess promising application prospects.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A liquid ground film material, characterized in that: The invention comprises tamarind polysaccharide benzoate, a modification aid and water, wherein the mass percentage of the tamarind polysaccharide benzoate is 1-3%, and the mass percentage of the modification aid is 2.3-8.7%; The tamarind polysaccharide benzoate is prepared by esterification reaction of benzoic anhydride and tamarind polysaccharide, wherein the mass ratio of benzoic anhydride to tamarind polysaccharide is 1:1 to 4:1; The modification auxiliary agent includes galactomannan and waterborne polyurethane, and the mass ratio of the galactomannan, waterborne polyurethane and tamarind polysaccharide benzoate is 0.5-1.5:0.5-2.5:1-3; The modification auxiliary agent further comprises a plasticizer and saponin, wherein the plasticizer is composed of urea, polyvinyl alcohol and glycerol in a mass ratio of 0.5-1.5:0.25-1.5:0.5-1.

5.

2. The liquid ground film material according to claim 1, characterized in that: The preparation of the tamarind polysaccharide benzoate comprises: At a temperature of 30-50°C, tamarind polysaccharide is dispersed in N,N-dimethylformamide, 4-dimethylaminopyridine and anhydrous potassium carbonate are added, and activated for 1-3 hours; The benzoic anhydride solution is added to the activated tamarind polysaccharide solution and the esterification reaction is carried out for 10 to 12 hours.

3. The liquid ground film material according to claim 2, characterized in that: The mass ratio of N,N-dimethylformamide to tamarind polysaccharide is 50:1 to 20:1; the mass ratio of 4-dimethylaminopyridine to tamarind polysaccharide is 2:1 to 4:1; the mass ratio of anhydrous potassium carbonate to tamarind polysaccharide is 0.2:1 to 0.5:1; And / or, the benzoic anhydride solution is obtained by dissolving benzoic anhydride in N,N-dimethylformamide.

4. The liquid ground film material according to claim 1, characterized in that: The liquid mulch material is composed of the following components in percentage by mass: 1-3% of tamarind polysaccharide benzoate, 0.5-1.5% of galactomannan, 0.5-2.5% of waterborne polyurethane, 0.5-1.5% of urea, 0.25-1.5% of polyvinyl alcohol, 0.5-1.5% of glycerol, 0.05-0.2% of saponin and the balance of water.

5. The method for preparing the liquid ground film material according to any one of claims 1 to 4, characterized in that: The following steps are involved: At a temperature of 75-90° C., tamarind polysaccharide benzoate is dissolved in water, and galactomannan, waterborne polyurethane, urea, polyvinyl alcohol, glycerol and saponin are added and blended, and stirred at a constant temperature for 40-70 minutes.

6. A method for using a liquid ground film material, characterized in that: The method comprises spraying the liquid ground film material according to any one of claims 1 to 4 on the soil surface to form a film, wherein the spraying amount of the liquid ground film material is 1 to 2.5 kg / m 2 .

7. The method for using the liquid ground film material according to claim 6, characterized in that: After film formation, the thickness of the liquid film is 50 to 90 μm, the stress is 10 to 25 MPa, the strain is 50 to 80%, the haze is more than 85%, and it blocks more than 95% of ultraviolet rays.

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