A bio-based fiber planting blanket for sandy land regreening and preparation method thereof

Abstract

The invention discloses a bio-based fiber planting blanket for sandy land greening and a preparation method thereof, belonging to the field of ecological restoration technology. The bio-based fiber planting blanket for sandy land greening comprises a planting blanket substrate, and the planting blanket substrate undergoes alkaline etching, and then, under the action of a thermal initiator, undergoes a graft copolymerization reaction with a mixed monomer in a treatment liquid to obtain a bio-based fiber planting blanket for sandy land greening, wherein the mixed monomer comprises a hydrophilic monomer and a lignin monomer. The preparation method comprises the following steps: a first step, alkaline etching the planting blanket substrate, taking it out, washing and drying it, to obtain a pre-treated planting blanket; a second step, adding the pre-treated planting blanket into the treatment liquid for graft copolymerization to obtain a bio-based fiber planting blanket for sandy land greening. The bio-based fiber planting blanket not only has good aging resistance and weather resistance, but also has a certain water retention effect, and can be used in high temperature and drought environments to solidify the surface and conserve surface moisture.

Description

Technical Field

[0001] The invention belongs to the technical field of ecological restoration, and in particular relates to a bio-based fiber planting blanket for sandy land regreening and a preparation method thereof. Background Art

[0002] Bio-based fiber planting blankets can be used to regreen sandy land. This material has the functions of moisturizing, retaining water, and saving water. It can cover a large area of ​​the surface, conserve and cultivate green plant seeds and seedlings, and naturally degrade into organic fertilizer within half a year without secondary pollution. It is suitable for the management of desertified saline-alkali land. In addition, plant fiber blanket technology transforms surplus agricultural resources into ecological environmental greening care products, which are suitable for sandy soil, hillsides, rivers, mining area reclamation and other scenarios. Environmentally friendly vegetation blankets are made of rice, wheat, straw, coconut palm fiber, etc., which can effectively resist water and wind erosion, solidify the surface, conserve surface moisture, and are suitable for harsh environments such as deserts.

[0003] The patent application with publication number CN110089234A discloses a method for preparing a vegetation blanket for restoration of degraded grasslands, in which a needle-punched felt made of kapok fiber, waste cotton fiber, and coconut shell fiber is used as a water storage layer by non-woven needle-punching technology, and a biomass crust is used as a seed layer. A thin non-woven fabric made of jute and waste cotton fiber is made by wet non-woven technology, and finally the water storage layer, seed layer, and wet non-woven fabric are knitted together using straw plants. However, in outdoor environments, planting blankets need to withstand the test of natural factors such as wind, sun, and rain. The various components of this composite planting blanket may age, degrade, and break after long-term use, reducing the service life and protective effect of the planting blanket. For example, thin non-woven fabrics made of jute and waste cotton fibers may easily become brittle and break under ultraviolet irradiation, and biomass crusts may gradually disappear under rain erosion, affecting the function of the seed layer. Summary of the invention

[0004] The object of the present invention is to provide a bio-based fiber planting blanket for sandy land regreening and a preparation method thereof, so as to solve the problem of poor weather resistance of the planting blanket.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A bio-based fiber planting blanket for sandy land greening includes a planting blanket substrate. After the planting blanket substrate is alkaline-etched, it undergoes a graft copolymerization reaction with mixed monomers in a treatment liquid under the action of a thermal initiator to obtain a bio-based fiber planting blanket for sandy land greening, wherein the mixed monomers include a hydrophilic monomer and a lignin monomer.

[0007] As a further preferred solution of the present invention, the mass ratio of the hydrophilic monomer to the lignin monomer in the treatment liquid is 10:1-3; the mass fraction of the mixed monomer in the treatment liquid is 30%. The lignin monomer introduces a hydrophobic segment, and the introduction of an appropriate hydrophobic segment can form a non-polar hydrophobic micro-region, which is closely arranged to achieve physical cross-linking, forming a stable three-dimensional network structure, increasing the rigidity and toughness of the water storage network, improving its ability to anchor water molecules, and reducing the diffusion capacity of water molecules, thereby achieving a better water retention effect.

[0008] As a further preferred solution of the present invention, the thermal initiator includes dibenzoyl peroxide and ammonium persulfate, and the mass ratio of dibenzoyl peroxide to ammonium persulfate is 1:1; the added amount of the initiator is 1% to 3% of the mass of the mixed monomer. Dibenzoyl peroxide is hydrophobic, and ammonium persulfate has good water solubility, and is suitable for the graft polymerization reaction in the system of the present invention.

[0009] As a further preferred embodiment of the present invention, the hydrophilic monomer is one of acrylic acid, methacrylic acid and fumaric acid.

[0010] As a further preferred embodiment of the present invention, the lignin monomer is obtained by reacting lignin sulfonate with unsaturated acyl chloride.

[0011] As a further preferred embodiment of the present invention, the lignin monomer is prepared by the following steps:

[0012] Under the protection of an inert atmosphere and an ice-water bath, lignin sulfonate is added to a solvent, triethylamine is added and stirred for dispersion, and then unsaturated acyl chloride is added. After the addition is complete, the temperature is raised to 35-40° C., and the reaction is stirred. The product is filtered, precipitated in ethanol, centrifuged and washed, and vacuum dried to constant weight to obtain lignin monomer.

[0013] As a further preferred embodiment of the present invention, the unsaturated acid chloride is one of acryloyl chloride, 10-undecenyl chloride and 5-hexenoyl chloride;

[0014] The usage ratio of the lignin sulfonate, triethylamine and unsaturated acid chloride is 5g: 0.009mol-0.01mol: 0.009mol-0.01mol.

[0015] A method for preparing a bio-based fiber planting blanket for sandy land regreening comprises the following steps:

[0016] The first step is to alkaline-etch the planting blanket substrate, take it out, wash it with water and dry it, and obtain a pre-treated planting blanket;

[0017] The second step is to add the pretreated planting blanket into the treatment liquid for graft copolymerization: the temperature is raised to 80°C under nitrogen protection conditions, and the reaction is carried out for 50-80 minutes. After the reaction is completed, it is washed with water, added into water for boiling, and dried at 60-80°C to obtain a bio-based fiber planting blanket for sandy land regreening.

[0018] As a further preferred embodiment of the present invention, the planting blanket substrate is prepared by the following steps:

[0019] The polyester fiber and cotton fiber are used as raw materials, which are overlapped and reinforced by needle punching to obtain a planting blanket matrix; the polyester fiber can be prepared from recycled polyester materials to improve the environmental friendliness of the planting blanket.

[0020] The needling depth of the needling reinforcement is 8-12 mm, the needling frequency is 500-700 times / min, and the mass ratio of the polyester fiber to the cotton fiber is 4: 1. Different needling depths and needling frequencies can be selected according to needs to suit different application scenarios.

[0021] As a further preferred solution of the present invention, the alkaline etching process includes adding the planting blanket substrate into a 0.3-0.5 mol / L sodium hydroxide aqueous solution and immersing it at 100° C. for 2 hours. Alkaline etching exposes more active groups, which is beneficial to the subsequent grafting reaction.

[0022] Beneficial effects of the present invention:

[0023] The planting blanket prepared by the present invention has good resistance to ultraviolet aging. The planting blanket substrate is subjected to alkaline erosion to obtain a pre-treated planting blanket that is conducive to grafting reaction. Then, a free radical copolymerization reaction occurs under the action of a thermal initiator, and hydrophilic monomers and lignin monomers are grafted onto the pre-treated planting blanket to obtain a bio-based fiber planting blanket for sandy land regreening. The bio-based fiber planting blanket not only has good aging resistance and weather resistance, but also has a certain water retention effect, and can be used in high temperature and drought environments to solidify the surface and conserve surface moisture. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Preparation Example 1

[0026] This preparation example prepares lignin monomer, including the following steps:

[0027] Under the protection of an inert atmosphere and an ice-water bath, 5 g of lignin sulfonate (calcium lignin sulfonate) was added to 50 mL of a solvent (N, N-dimethylacetamide), 0.009 mol of triethylamine was added and stirred for dispersion, and then 0.009 mol-0.01 mol of unsaturated acyl chloride (acryloyl chloride) was added. After the addition, the temperature was raised to 40°C, and the reaction was stirred for 8 hours. The product was filtered, precipitated in ethanol, washed by centrifugation, and dried in a vacuum at 50°C to constant weight to obtain a lignin monomer.

[0028] Preparation Example 2

[0029] This preparation example prepares lignin monomer, including the following steps:

[0030] Under the protection of an inert atmosphere and an ice-water bath, 5 g of lignin sulfonate (calcium lignin sulfonate) was added to 50 mL of a solvent (N, N-dimethylacetamide), 0.01 mol of triethylamine was added and stirred for dispersion, and then 0.01 mol of an unsaturated acyl chloride (acryloyl chloride) was added. After the addition, the temperature was raised to 40 ° C, and the reaction was stirred for 8 hours. The product was filtered, precipitated in ethanol, centrifuged and washed, and vacuum dried at 50 ° C to constant weight to obtain a lignin monomer.

[0031] Example 1

[0032] A method for preparing a bio-based fiber planting blanket for sandy land regreening comprises the following steps:

[0033] The first step is to use polyester fiber and cotton fiber with a mass ratio of 4:1 as raw materials, overlap and reinforce them with needle punching to obtain a planting blanket substrate, and then ultrasonically wash the planting blanket substrate with a needle punching depth of 12 mm and a needle punching frequency of 700 times / min, add 0.3 mol / L sodium hydroxide aqueous solution and soak it at 100°C for 2 hours, take it out and wash it with water and dry it to obtain a pretreated planting blanket;

[0034] The second step is to add the washed and dried pre-treated planting blanket into the treatment liquid, heat it to 80°C under nitrogen protection, react for 50 minutes, wash it with water, boil it in water to remove the homopolymer, and dry it at 60°C to obtain the bio-based fiber planting blanket for sandy land regreening. The treatment liquid includes a mixed monomer and a thermal initiator (the mass ratio of dibenzoyl peroxide and ammonium persulfate is 1:1), the mixed monomer includes a hydrophilic monomer (acrylic acid) and the lignin monomer prepared in Preparation Example 1, the mass ratio of the hydrophilic monomer to the lignin monomer is 10:1, and the amount of the initiator added is 1% of the mass of the mixed monomer; the mass fraction of the mixed monomer in the treatment liquid is 30%.

[0035] Example 2

[0036] A method for preparing a bio-based fiber planting blanket for sandy land regreening comprises the following steps:

[0037] The first step is to use polyester fiber and cotton fiber with a mass ratio of 4:1 as raw materials, overlap and reinforce them with needle punching to obtain a planting blanket substrate, and then ultrasonically wash the planting blanket substrate with a needle punching depth of 12 mm and a needle punching frequency of 700 times / min, add 0.3 mol / L sodium hydroxide aqueous solution and soak it at 100°C for 2 hours, take it out and wash it with water and dry it to obtain a pretreated planting blanket;

[0038] The second step is to add the pre-treated planting blanket after washing and drying into the treatment liquid, heat it to 80°C under nitrogen protection, react for 80 minutes, and after the reaction, wash it with water, add it into water and boil it to remove the homopolymer, and dry it at 80°C to obtain the bio-based fiber planting blanket for sandy land greening. The treatment liquid includes a mixed monomer and a thermal initiator (the mass ratio of dibenzoyl peroxide and ammonium persulfate is 1:1), and the mixed monomer includes a hydrophilic monomer (acrylic acid) and the lignin monomer prepared in Preparation Example 2. The mass ratio of the hydrophilic monomer to the lignin monomer is 10:1, and the amount of the initiator added is 1% of the mass of the mixed monomer; the mass fraction of the mixed monomer in the treatment liquid is 30%.

[0039] Example 3

[0040] A method for preparing a bio-based fiber planting blanket for sandy land regreening comprises the following steps:

[0041] The first step is to use polyester fiber and cotton fiber with a mass ratio of 4:1 as raw materials, overlap and reinforce them with needle punching to obtain a planting blanket substrate, and then ultrasonically wash the planting blanket substrate with a needle punching depth of 12 mm and a needle punching frequency of 700 times / min, add 0.3 mol / L sodium hydroxide aqueous solution and soak it at 100°C for 2 hours, take it out and wash it with water and dry it to obtain a pretreated planting blanket;

[0042] The second step is to add the washed and dried pre-treated planting blanket into the treatment liquid, heat it to 80°C under nitrogen protection, react for 80 minutes, and after the reaction, wash it with water, add it into water and boil it to remove the homopolymer, and dry it at 80°C to obtain the bio-based fiber planting blanket for sandy land greening. The treatment liquid includes a mixed monomer and a thermal initiator (the mass ratio of dibenzoyl peroxide and ammonium persulfate is 1:1), and the mixed monomer includes a hydrophilic monomer (acrylic acid) and the lignin monomer prepared in Preparation Example 2. The mass ratio of the hydrophilic monomer to the lignin monomer is 10:3, and the amount of the initiator added is 3% of the mass of the mixed monomer; the mass fraction of the mixed monomer in the treatment liquid is 30%.

[0043] Example 4

[0044] Compared with Example 3, the mass ratio of the hydrophilic monomer to the lignin monomer in this example is adjusted to 10:2, and the other raw materials and preparation process remain the same as those in Example 3.

[0045] Example 5

[0046] Compared with Example 3, the concentration of the sodium hydroxide aqueous solution in this example is adjusted to 0.4 mol / L, and the other raw materials and preparation process remain the same as those in Example 3.

[0047] Example 6

[0048] Compared with Example 3, the concentration of the sodium hydroxide aqueous solution in this example is adjusted to 0.5 mol / L, and the other raw materials and preparation process remain the same as those in Example 3.

[0049] Comparative Example 1

[0050] Compared with Example 6, the mass ratio of the hydrophilic monomer to the lignin monomer in this comparative example is adjusted to 10:6, and the other raw materials and preparation process remain the same as those in Example 6.

[0051] Comparative Example 2

[0052] Compared with Example 6, this comparative example does not add lignin monomer, and the other raw materials and preparation process remain the same as those of Example 6.

[0053] Comparative Example 3

[0054] Compared with Example 6, the comparative example replaced the lignin monomer with an equal mass of calcium lignin sulfonate, and the other raw materials and preparation process remained the same as those of Example 6.

[0055] Comparative Example 4

[0056] Compared with Example 6, the concentration of the sodium hydroxide aqueous solution in this comparative example was adjusted to 1 mol / L, and the remaining raw materials and preparation process remained the same as those in Example 6.

[0057] The performance of Examples 1 to 6 and Comparative Examples 1 to 4 was tested by artificial accelerated aging: they were placed in a UV aging box at a light intensity of 1 W / m 2， The temperature in the box is 60℃, and the artificial accelerated aging test is carried out. Samples are taken every 7 days for standby use. The tensile test is carried out according to the standard GB / T3923.1-2013; the results are shown in Table 1:

[0058] Table 1

[0059]

[0060] The prepared planting blanket was tested by artificial accelerated aging at different times. From the test results recorded in Table 1, it can be seen that the planting blanket prepared by the present invention has good resistance to ultraviolet aging. By alkaline etching (soaking in sodium hydroxide aqueous solution) of the planting blanket substrate to expose more active groups (such as hydroxyl groups), a pre-treated planting blanket that is conducive to grafting reaction is obtained, and then a free radical copolymerization reaction occurs under the action of a thermal initiator, and the hydrophilic monomer and the lignin monomer are grafted and copolymerized onto the pre-treated planting blanket to obtain a bio-based fiber planting blanket for sandy land greening. According to the data comparison of Example 3 and Comparative Example 4, in the alkali solution treatment, the concentration of sodium hydroxide should not be too high, which will cause excessive erosion of the fiber surface and affect the mechanical properties of the planting blanket. According to the data comparison of Examples 3-6, it can be seen that too low or too low will result in a small number of active groups, which is not conducive to the subsequent graft polymerization reaction and affects the aging resistance.

[0061] The water retention rate of the planting blankets prepared in Example 6 and Comparative Examples 1 to 4 was tested. The samples of the same weight were immersed in water for 50 hours. After being taken out until no water drops, the weight of the samples was weighed and recorded as m1. The samples saturated with liquid were placed in a blast drying oven with a set temperature of 50°C. The mass of the samples after 5 hours was recorded as m n ; Water retention rate = [1-(m1-m n ) / m1]×100%=m n / m1×100%; the results are shown in Table 2 below:

[0062] Table 2

[0063]

[0064] According to the water retention effect recorded in Table 2, the planting blanket prepared by the present invention has a good water retention effect. By adding lignin monomers to the treatment liquid, hydrophobic segments are introduced. The introduction of appropriate hydrophobic segments can form non-polar hydrophobic micro-regions. These hydrophobic regions are closely arranged to achieve physical cross-linking, forming a stable three-dimensional network structure, increasing the rigidity and toughness of the water storage network, improving its anchoring ability for water molecules, and reducing the diffusion capacity of water molecules, thereby achieving a better water retention effect. However, the introduction of too much lignin monomer is not conducive to improving the diffusion of water molecules and affecting the absorption and storage of water. Therefore, when the proportion of lignin in Comparative Example 1 is high, the water retention effect will also be poor. The calcium lignin sulfonate in Comparative Example 3 only participates in the preparation of the planting blanket by adsorption, which is equivalent to introducing a hydrophobic material on the surface of the planting blanket, which is more unfavorable for the retention of water.

[0065] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0066] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A bio-based fiber planting blanket for sandy land regreening, characterized in that: The invention comprises a planting blanket substrate, which is etched with alkaline and then, under the action of a thermal initiator, undergoes a graft copolymerization reaction with mixed monomers in a treatment liquid to obtain a bio-based fiber planting blanket for sandy land regreening, wherein the mixed monomers include a hydrophilic monomer and a lignin monomer.

2. The bio-based fiber planting blanket for sandy land regreening according to claim 1, characterized in that: The mass ratio of the hydrophilic monomer to the lignin monomer in the mixed monomer is 10:1-3; the mass fraction of the mixed monomer in the treatment liquid is 30%.

3. The bio-based fiber planting blanket for sandy land regreening according to claim 1, characterized in that: The thermal initiator comprises dibenzoyl peroxide and ammonium persulfate, and the mass ratio of dibenzoyl peroxide to ammonium persulfate is 1:1; the added amount of the initiator is 1% to 3% of the mass of the mixed monomers.

4. The bio-based fiber planting blanket for sandy land regreening according to claim 1, characterized in that: The hydrophilic monomer is one of acrylic acid, methacrylic acid and fumaric acid.

5. The bio-based fiber planting blanket for sandy land regreening according to claim 1, characterized in that: The lignin monomer is obtained by reacting lignin sulfonate with unsaturated acyl chloride.

6. The bio-based fiber planting blanket for sandy land regreening according to claim 1, characterized in that: The lignin monomer is prepared by the following steps: Under the protection of an inert atmosphere and an ice-water bath, lignin sulfonate is added to a solvent, triethylamine is added and stirred for dispersion, and then unsaturated acyl chloride is added. After the addition is complete, the temperature is raised to 35-40° C., and the reaction is stirred. The product is filtered, precipitated in ethanol, centrifuged and washed, and vacuum dried to constant weight to obtain lignin monomer.

7. The bio-based fiber planting blanket for sandy land restoration according to claim 6, characterized in that: The unsaturated acid chloride is one of acryloyl chloride, 10-undecenyl chloride and 5-hexenoyl chloride; The usage ratio of the lignin sulfonate, triethylamine and unsaturated acid chloride is 5g: 0.009mol-0.01mol: 0.009mol-0.01mol.

8. A method for preparing a bio-based fiber planting blanket for sandy land regreening as claimed in any one of claims 1 to 7, characterized in that: The steps include: The first step is to alkaline-etch the planting blanket substrate, take it out, wash it with water and dry it, and obtain a pre-treated planting blanket; The second step is to add the pretreated planting blanket into the treatment liquid for graft copolymerization: the temperature is raised to 80°C under nitrogen protection conditions, and the reaction is carried out for 50-80 minutes. After the reaction is completed, it is washed with water, added into water for boiling, and dried at 60-80°C to obtain a bio-based fiber planting blanket for sandy land regreening.

9. The method for preparing a bio-based fiber planting blanket for sandy land restoration according to claim 8, characterized in that: The planting blanket substrate is prepared by the following steps: The polyester fiber and the cotton fiber with a mass ratio of 4:1 are used as raw materials, and the fibers are laminated and reinforced by needle punching to obtain a planting blanket substrate; the needle punching depth of the needle punching reinforcement is 8-12 mm, and the needle punching frequency is 500-700 times / min.

10. The method for preparing a bio-based fiber planting blanket for sandy land restoration according to claim 8, characterized in that: The alkaline etching process includes adding the planting blanket substrate into a 0.3-0.5 mol / L sodium hydroxide aqueous solution and immersing the substrate at 100° C. for 2 hours.

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