Armored lignin-based articles and methods for making the same

Abstract

The present application relates to a kind of " armoring " lignin-based product and its preparation method.The preparation method of the present application can greatly protect lignin, so that it can play a long-term stable role while enhancing its other properties to a certain extent, the lignin-based product obtained from " armoring " has excellent air, moisture and ultraviolet blocking ability, and excellent antibacterial performance and mechanical properties and is biodegradable, which can be widely used in food preservation, food packaging and tableware packaging and other fields.

Description

Technical Field

[0001] This invention relates to a product based on "armor" lignin and its preparation method, belonging to the field of green food packaging material technology. Background Technology

[0002] Due to its inherent antibacterial, antioxidant, and UV-blocking properties, lignin has become a promising material for applications in environmentally friendly food preservation. Currently, lignin also has applications in the packaging materials industry. However, lignin has poor solvent resistance and is easily damaged, leading to a decline in its performance. How to effectively protect lignin and ensure its long-term stable function has become an urgent problem to be solved. Summary of the Invention

[0003] The problem the invention aims to solve

[0004] The purpose of this invention is to provide a product based on "armored" lignin and its preparation method. The preparation method of this invention can greatly protect the lignin, enabling it to function stably for a long time while enhancing its other properties. The resulting product based on "armored" lignin has excellent barrier properties against air, moisture, and ultraviolet radiation, as well as excellent antibacterial and mechanical properties, and is biodegradable. It can be widely used in food preservation, food packaging, and tableware packaging.

[0005] Solution for solving the problem

[0006] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by "armoring" lignin, the armored lignin is more stable and can play its corresponding role for a long time and effectively, thus solving the above-mentioned problems and completing the present invention.

[0007] That is, the present invention is as follows.

[0008] [1]. A method for preparing an article based on "armor" lignin, wherein the preparation method includes:

[0009] Process A: A mixture of lignin, acrylate functional group derivatives of natural oils, and polyvinyl alcohol is used to obtain "armored" lignin nanoparticles; and

[0010] Step B: Prepare "armored" lignin-based products by electrospinning a spinning solution containing the "armored" lignin nanoparticles.

[0011] [2]. According to the preparation method described in [1], wherein the acrylate functional group derivative of the natural oil includes the acrylate functional group derivative of soybean oil;

[0012] Preferably, the acrylate functional group derivative of the soybean oil includes epoxidized soybean oil acrylate.

[0013] [3]. According to the preparation method described in [2], wherein step A includes:

[0014] Step A1: A mixture comprising an epoxy compound and acrylic acid is mixed with at least one selected from the group consisting of polymerization inhibitors and catalysts to obtain an acrylate functional group derivative of natural oil.

[0015] Step A2: Mix lignin, acrylate functional group derivatives of the natural oil obtained in Step A1, and polyvinyl alcohol to obtain "armored" lignin nanoparticles.

[0016] [4]. According to the preparation method described in [3], wherein step A1 satisfies at least one of the following:

[0017] (a) The ratio of epoxy groups in the epoxy compound to carboxyl groups in the acrylic acid is 1:1 to 1.2:1;

[0018] (b) The epoxy compound comprises epoxidized soybean oil;

[0019] (c) The polymerization inhibitor is 4-methoxyphenol;

[0020] (d) The catalyst is anthraquinone;

[0021] (e) The mass ratio of the epoxy compound to the acrylic acid is 14:1 to 15:1;

[0022] (f) The mass ratio of the polymerization inhibitor to the epoxy compound is 1:1000 to 1:900;

[0023] (g) The mass ratio of the catalyst to the epoxide is 1:77 to 1:78;

[0024] (h) Stop the reaction when the acid value of the reactants is below 8 mg / g.

[0025] [5]. The preparation method according to any one of [1] to [4], wherein, in step A or step A2, the mass ratio of the lignin to the acrylate functional group derivative of the natural oil is 1:1 to 1:2.

[0026] [6]. The preparation method according to any one of [1] to [5], wherein step B includes the following steps:

[0027] Step B1: Mix the "armor" lignin nanoparticles, cellulose acetate, and organic solvent to obtain a spinning solution;

[0028] Step B2: Prepare "armored" lignin-based products by electrospinning the spinning solution.

[0029] [7]. According to the preparation method described in [6], wherein step B1 satisfies at least one of the following:

[0030] (i) The organic solvent comprises acetone and N,N-dimethylformamide;

[0031] (j) Cellulose acetate accounts for 40-45% of the total mass of the spinning solution;

[0032] (k) The mass of acetone accounts for 0.1 to 0.2% of the total mass of the spinning solution;

[0033] (l) N,N-dimethylformamide accounts for 57-60% of the total mass of the spinning solution;

[0034] (m) "Armor" lignin nanoparticles account for 1-2% of the total mass of the spinning solution.

[0035] [8]. According to the preparation method described in [6], in step B2, the conditions for electrospinning are: the volume of the syringe is 10.00 mL, the syringe is equipped with a 1.5 mm needle, the controllable extrusion rate is 1.00 mL / min, and the voltage applied to the needle is 20.00 kV.

[0036] [9]. An article based on "armor" lignin, wherein the article based on "armor" lignin is obtained by the preparation method according to any one of [1] to [8].

[0037]

[10] . The article according to [9], wherein the article based on "armor" lignin contains 1 to 3% by mass of "armor" lignin nanoparticles;

[0038] Preferably, the "armored" lignin nanoparticles include a core and a shell covering at least a portion of the outer surface of the core.

[0039] The core contains lignin.

[0040] The shell contains acrylate functional group derivatives of natural oils and polyvinyl alcohol.

[0041] The effects of the invention

[0042] The preparation method of this invention can protect lignin to a great extent, enabling it to function stably for a long time while enhancing its other properties. The resulting "armored" lignin-based products have excellent ability to block air, moisture and ultraviolet rays, as well as excellent antibacterial and mechanical properties and are biodegradable. They can be widely used in food preservation, food packaging and tableware packaging. Attached Figure Description

[0043] Figure 1a The preparation mechanism of "armored" lignin nanoparticles was demonstrated.

[0044] Figure 1b The epoxidized soybean oil acrylate (AESO) shown in Examples 1-3 is illustrated. 1 H NMR spectrum.

[0045] Figure 1c The FTIR characterization of the “armored” lignin nanoparticles in Examples 1–3 is shown.

[0046] Figure 2a Scanning electron microscope images of the "armored" lignin nanoparticles prepared in Examples 1-3.

[0047] Figure 2b These are transmission electron microscope images of the "armored" lignin nanoparticles at different magnifications in Example 1.

[0048] Figure 2c The formation process of the "armored" lignin nanoparticles in Example 1 is shown.

[0049] Figure 2d The size distribution of the “armored” lignin nanoparticles in Examples 1-3 is shown.

[0050] Figure 3a Scanning electron microscope images of the "armor" lignin-based products (barrier biodegradable antibacterial food preservation film with "armor" lignin content of 3%) in Examples 1-3.

[0051] Figure 3b Thermogravimetric analysis of the "armored" lignin-based products of Examples 1-3 is shown.

[0052] Figure 3c The elongation and tensile strength of the "armored" lignin-based articles of Examples 1-3 are shown.

[0053] Figure 3d The visible and ultraviolet light transmittance of the "armored" lignin-based articles of Examples 1-3 are shown.

[0054] Figure 3eThe gas separation performance of the "armored" lignin-based products of Examples 1-3 is shown.

[0055] Figure 3f The water contact angles of the "armored" lignin-based products of Examples 1-3 are shown.

[0056] Figure 4a The antibacterial activity of the "armored" lignin-based products of Examples 1-3 is shown.

[0057] Figure 4b The practical application of the antioxidant properties of the "armored" lignin-based products of Examples 1-3 is shown.

[0058] Figure 4c The natural degradation properties of the "armored" lignin-based products of Examples 1-3 are shown. Detailed Implementation

[0059] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0060] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0061] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0062] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0063] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0064] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0065] <Preparation method of products based on "armor" lignin>

[0066] In a first aspect of the present invention, a method for preparing an article based on "armor" lignin is provided, comprising:

[0067] Process A: A mixture of lignin, acrylate functional group derivatives of natural oils, and polyvinyl alcohol is used to obtain "armored" lignin nanoparticles; and

[0068] Step B: Prepare "armored" lignin-based products by electrospinning a spinning solution containing the above-mentioned "armored" lignin nanoparticles.

[0069] This invention protects lignin by "armoring" it. The lignin protected by "armor" is more stable and can play its corresponding role for a long time and effectively. The resulting products based on "armored" lignin have excellent ability to block air, moisture and ultraviolet rays, as well as excellent antibacterial and mechanical properties and are biodegradable. They can be widely used in food preservation, food packaging and tableware packaging.

[0070] (Process A)

[0071] In step A, lignin, acrylate functional group derivatives of natural oils, and polyvinyl alcohol are mixed to obtain "armored" lignin nanoparticles.

[0072] Lignin is a high-molecular-weight phenolic compound that participates in the lignification of higher plants. It is also known as lignin. The molecular weight varies depending on the type of biomass, extraction method, and analytical method, but the reported number-average molecular weight is generally 2,400 to 9,700 (Biofuels Bioproducts & Biorefinering, Volume 8, Issue 6, 836-856 (2014)).

[0073] Lignin can be lignin separated from plants through physical pulverization or chemical decomposition during the process of separating lignin from cellulose and hemicellulose. Furthermore, it can also include lignin derivatives produced during the separation process by acetylation, methylation, halogenation, nitration, sulfonation, phenolation, or reaction with sodium sulfide or hydrogen sulfide using the solvents and catalysts employed.

[0074] Methods for separating and extracting lignin from plants include the kraft paper method, the sulfuric acid method, and the explosion method. Currently, most lignin produced in large quantities is obtained as a residue during the manufacture of cellulose, a raw material for paper and bioethanol. Among the lignin that can be obtained, lignin sulfonates, mainly byproducts of the sulfuric acid method, can be listed. Other types include alkali lignin, organic solvent lignin, solvent-decomposed lignin, dioxane lignin, ground wood lignin, and explosion lignin. Regardless of the extraction method, the lignin used in this invention can be any of the lignin described above. There are no particular limitations on the plant material used, as long as lignin can be extracted from it; examples include bamboo, straw, wheat straw, poplar, eucalyptus, acacia, fir, rice straw, wheat straw, cypress, locust, willow, poplar, bagasse, corn, sugarcane, grains, eucalyptus, and sugarcane awns. Commercially available lignin can also be used.

[0075] In some preferred embodiments, the lignin preferably comprises at least one of alkali lignin, lignin sulfonate, organic solvent pulping lignin, or lignin isolated from bamboo, straw, wheat straw, poplar, eucalyptus or acacia.

[0076] Alkali lignin can be prepared from black liquor obtained by cooking wood chips with caustic soda (NaOH). The ratio of wood chips to cooking liquor during cooking can be set to, for example, 1.0 to 40 L / g.

[0077] In the above-mentioned alkaline cooking process, in addition to caustic soda (NaOH), various cooking aids can also be used. For example, 0.01 to 5% by mass of quinone can also be added per unit of oven-dried scrap.

[0078] The quinones used are quinone compounds, hydroquinone compounds, or precursors thereof that are known as cooking aids, and at least one compound selected from these substances may be used. Examples of such compounds include: anthraquinones, dihydroanthraquinones, tetrahydroanthraquinones, methylanthraquinones, sugar compounds, or precursors thereof.

[0079] The obtained cooking liquor can be used directly as alkali lignin, or the substance obtained by purifying lignin from the obtained cooking liquor can be used as alkali lignin. Powdered alkali lignin can be obtained by spray drying and pulverizing an alkaline solution of alkali lignin (or the obtained cooking liquor), or acid-precipitated alkali lignin can be obtained by precipitating an alkaline solution of alkali lignin with acid.

[0080] In some preferred embodiments, lignin may not require purification.

[0081] Lignosulfonates are preferably sodium, potassium, calcium, magnesium, or ammonium salts, or substituted ammonium salts of grades 1 to 4. Specifically, examples include sodium lignosulfonate, potassium lignosulfonate, calcium lignosulfonate, magnesium lignosulfonate, and ammonium lignosulfonate. Lignosulfonates are commercially available products.

[0082] The lignin used in this invention can be in powder or liquid form, preferably in powder form. As a liquid lignin, for example, the powdered lignin can be dissolved in a suitable solvent (e.g., water, aqueous sodium hydroxide solution, etc.) to prepare a liquid lignin.

[0083] "Acrylate functional group derivatives of natural oils" can be prepared by an addition reaction of an oil component having functional groups with acrylic acid or a functional group derivative of acrylic acid. In some embodiments, the oil is an unsaturated oil that is epoxidized and then esterified with acrylic acid to provide oil acrylates.

[0084] Examples of natural oils include at least one of soybean oil, flaxseed oil, tung oil, coconut oil, corn oil, cottonseed oil, olive oil, palm oil, palm kernel oil, and peanut oil.

[0085] In some preferred embodiments, the acrylate functional group derivatives of natural oils include acrylate functional group derivatives of soybean oil.

[0086] In some preferred embodiments, the acrylate functional group derivatives of the aforementioned soybean oil include epoxidized soybean oil acrylate. In this preferred embodiment, epoxidized soybean oil is reacted with acrylic acid to provide β-hydroxyacrylate, yielding epoxidized soybean oil acrylate.

[0087] In some preferred embodiments, step A further includes:

[0088] Step A1: A mixture comprising an epoxy compound and acrylic acid is mixed with at least one selected from the group consisting of polymerization inhibitors and catalysts to obtain an acrylate functional group derivative of natural oil.

[0089] Step A2: Mix lignin, acrylate functional group derivatives of the natural oil obtained in Step A1 above, and polyvinyl alcohol to obtain "armored" lignin nanoparticles.

[0090] In step A1, the ratio of epoxy groups in the epoxy compound to carboxyl groups in the acrylic acid is preferably 1:1 to 1.2:1. In some specific embodiments, the ratio of epoxy groups in the epoxy compound to carboxyl groups in the acrylic acid is 1:1, 1.1:1, or 1.2:1.

[0091] As an epoxide compound, it preferably contains epoxide-treated soybean oil.

[0092] 4-Methoxyphenol is preferred as a polymerization inhibitor.

[0093] Anthraquinone is preferred as a catalyst.

[0094] Epoxy compounds, acrylic acid, polymerization inhibitors, and catalysts are commercially available.

[0095] In some preferred embodiments, the mass ratio of epoxy compound to acrylic acid is 14:1 to 15:1. In some specific embodiments, the mass ratio of epoxy compound to acrylic acid is 14:1, 14.2:1, 14.5:1, 14.8:1, or 15:1.

[0096] In some preferred embodiments, the mass ratio of the polymerization inhibitor to the epoxide is 1:1000 to 1:900. In some specific embodiments, the mass ratio of the polymerization inhibitor to the epoxide is 1:1000, 1:980, 1:950, 1:920, or 1:900.

[0097] In some preferred embodiments, the mass ratio of catalyst to epoxide is 1:77 to 1:78.

[0098] In this invention, by setting the amounts of epoxy compound, acrylic acid, polymerization inhibitor and catalyst within the above-mentioned range, it is possible to obtain acrylate functional group derivatives of natural oils efficiently and well.

[0099] In process A1, the reaction is stopped when the acid value of the reactants is below 8 mg / g. The acid value is measured using a fully automated acid value analyzer.

[0100] In some preferred embodiments, step A1 preferably includes the following steps:

[0101] Step a1: Mix epoxidized soybean oil, acrylic acid and polymerization inhibitor, and stir at room temperature for 10 minutes at a stirring speed of 300 r / min;

[0102] Step a2: Add the catalyst to the mixture obtained in step a1 above, stir at 300 r / min and raise the temperature to 80℃. After 30 min, raise the temperature to 120℃ and measure the acid value of the reactants. Stop the reaction when the acid value is lower than 8 mg / g.

[0103] In steps A and A2 above, the mass ratio of lignin to the acrylate functional group derivative of natural oil is 1:1 to 1:2. In some specific embodiments, the mass ratio of lignin to the acrylate functional group derivative of natural oil is 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2. By setting the mass ratio of lignin to the acrylate functional group derivative of natural oil within the above range, "armored" lignin nanoparticles can be obtained efficiently and effectively.

[0104] In step A, it is preferable to mix a mixture of lignin, an acrylate functional group derivative of natural oil, and polyvinyl alcohol with at least one selected from the group consisting of butyl acetate and azobisisobutyronitrile.

[0105] In some preferred embodiments, the mass ratio of butyl acetate to lignin is 17.9:1 to 18.1:1, the mass of azobisisobutyronitrile (AIBN) added is 1.9 to 2.1% of the mass of lignin added, and the mass of the polyvinyl alcohol (PVA) / water mixed solution added is 17.1 to 18.9% of the mass of lignin added. By setting the amounts of butyl acetate, AIBN, and PVA / water mixed solution within the above ranges, "armored" lignin nanoparticles can be obtained efficiently and well.

[0106] In some preferred embodiments, step A or step A2 includes a multi-stage mixing step, which includes the following steps:

[0107] In the first stirring step, lignin, acrylate functional group derivatives of natural oil, polyvinyl alcohol / water mixed solution, and a mixture of at least one selected from the group consisting of butyl acetate and azobisisobutyronitrile are stirred at room temperature (23-25°C) at a first stirring speed, preferably 1200-1500 r / min.

[0108] The second stirring step involves sealing the mixture obtained from the first stirring step and stirring it at a temperature of 70°C at a second stirring speed of 900 r / min.

[0109] The third mixing step involves mixing the mixture obtained from the second mixing step in an open-air environment (at 23-25°C) at a third mixing speed of 900 r / min.

[0110] To better obtain "armored" lignin nanoparticles, the holding time of the first stirring speed in the first stirring step is preferably 1 to 2 hours, the holding time of the second stirring speed in the second stirring step is preferably 24 hours, and the holding time of the third stirring speed in the third stirring step is preferably 24 hours.

[0111] In some preferred embodiments, step A further includes: after step A2, washing and / or separating the substance obtained above.

[0112] There are no particular limitations on the specific cleaning method; for example, deionized water can be used. The number of cleaning cycles can be more than once, preferably five times.

[0113] There are no particular limitations on the specific method of separation; for example, centrifugation can be used. Centrifugation can be performed using, for example, horizontal or disc centrifuges. In some preferred embodiments, centrifugation is carried out at 8500–9000 rpm for 10–15 minutes.

[0114] Figure 1a The preparation mechanism of the "armored" lignin nanoparticles was demonstrated. For example... Figure 1a As shown, the "armored" lignin nanoparticles of the present invention include a core and a shell covering at least a portion of the outer surface of the core, thereby obtaining "armored" lignin nanoparticles with a lignin core and a surface coated with acrylate functional group derivatives of natural oils (e.g., epoxidized soybean oil acrylate (AESO)) and polyvinyl alcohol (PVA). Here, the shell can cover the entire outer surface of the core.

[0115] The core contains lignin. The shell contains acrylate functional group derivatives of natural oils (e.g., epoxidized soybean oil acrylate (AESO)) and polyvinyl alcohol (PVA). The core and shell are linked by carboxyl groups formed by the ring-opening reaction of the lignin with the epoxidized soybean oil acrylate.

[0116] (Process B)

[0117] In step B: the spinning solution containing the above-mentioned "armored" lignin nanoparticles is electrospinned to prepare "armored" lignin-based products.

[0118] In some preferred embodiments, step B preferably includes the following steps:

[0119] Step B1: Mix the above-mentioned "armor" lignin nanoparticles, cellulose acetate and organic solvent to obtain a spinning solution;

[0120] Step B2: Prepare products based on "armor" lignin by electrospinning the above spinning solution.

[0121] [Process B1]

[0122] Examples of organic solvents include acetone and / or N,N-dimethylformamide.

[0123] In some preferred embodiments, cellulose acetate and organic solvent are first mixed at a high speed of 500 r / min until completely dissolved, and then the "armor" lignin nanoparticles are added and stirred until completely dissolved.

[0124] In some preferred embodiments, cellulose acetate accounts for 40% to 45% of the total mass of the spinning solution; acetone accounts for 0.1% to 0.2% of the total mass of the spinning solution; N,N-dimethylformamide accounts for 57% to 60% of the total mass of the spinning solution; and "armored" lignin nanoparticles account for 1% to 2% of the total mass of the spinning solution.

[0125] In some specific embodiments, cellulose acetate accounts for 40%, 41%, 42%, 43%, 44%, or 45% of the total mass of the spinning solution; acetone accounts for 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, or 0.2% of the total mass of the spinning solution; N,N-dimethylformamide accounts for 57%, 58%, 59%, or 60% of the total mass of the spinning solution; and "armored" lignin nanoparticles account for 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2% of the total mass of the spinning solution.

[0126] [Process B2]

[0127] In some preferred embodiments, the spinning solution is preferably transferred to a syringe, extruded at a controlled rate using an injection pump, while a suitable voltage is applied to the needle tip. The nanofibers prepared by electrospinning are collected on a roller receiver covered with aluminum foil and dried to obtain an article based on "armored" lignin.

[0128] In some preferred embodiments, the syringe has a volume of 10.00 mL, is equipped with a 1.5 mm needle, has a controllable extrusion rate of 1.00 mL / min, and has an applied voltage of 20.00 kV.

[0129] In some preferred embodiments, the drying temperature is 80°C and the drying time is 2 hours.

[0130] The preparation method according to the present invention can yield lignin-based products with an "armored" lignin content of 1-3% by mass. By "armoring" the lignin, the lignin protected by the present invention becomes more stable and can exert its corresponding functions effectively and for a long time. The resulting lignin-based products have excellent barrier properties against air, moisture, and ultraviolet radiation, as well as excellent antibacterial and mechanical properties, and are biodegradable. They can be widely used in food preservation, food packaging, and tableware packaging.

[0131] <Products based on "armored" lignin>

[0132] In a second aspect of the invention, an article based on "armor" lignin is provided, which is obtained according to the preparation method described in the first aspect above.

[0133] In some preferred embodiments, the "armored" lignin-based article contains 1 to 3% by mass of "armored" lignin nanoparticles.

[0134] In some preferred embodiments, the "armored" lignin nanoparticles of the present invention include a core and a shell covering at least a portion of the outer surface of the core, thereby obtaining "armored" lignin nanoparticles with a lignin core and a surface coated with epoxidized soybean oil acrylate (AESO) and polyvinyl alcohol (PVA) as "armor". Here, the shell may cover the entire outer surface of the core.

[0135] The core contains lignin. The shell contains epoxidized soybean oil acrylate (AESO) and polyvinyl alcohol (PVA). The core and shell are linked by carboxyl groups formed by a ring-opening reaction between the hydroxyl groups of lignin and epoxidized soybean oil acrylate.

[0136] Example

[0137] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0138] Example 1

[0139] (1) Preparation of epoxidized soybean oil acrylate (AESO)

[0140] 60.00 g of epoxidized soybean oil (ESO) and 4.10 g of acrylic acid (AA) were mixed to maintain an epoxy group to carboxyl group ratio of 1.12:1. Then, 0.06 g of 4-methoxyphenol was added to the mixture, and the mixture was stirred at room temperature for 10 min (300 rpm). Next, 0.77 g of anthraquinone was slowly added to the mixture while stirring, and the temperature was raised to 80 °C. After 30 min, the temperature was further raised to 120 °C (300 rpm). The acid value of the reactants was measured periodically using an automated acid value analyzer, and the reaction was stopped when the acid value fell below 8 mg / g. The product was first poured into butanone, and after complete dissolution, it was poured into diethyl ether to precipitate. The precipitate was collected, and unreacted sample was removed to obtain the product, epoxidized soybean oil acrylate (AESO).

[0141] (2) Preparation of "armored" lignin nanoparticles

[0142] A mixture of 0.50 g lignin (OL, enzymatically hydrolyzed corn cob residual lignin manufactured by Shandong Longli Biotechnology Co., Ltd.), 0.50 g AESO prepared in step (1) above, 9.00 g butyl acetate, and 10.00 mg azobisisobutyronitrile was gradually added dropwise to 90.00 mL of PVA / water mixed solution (1 wt%), while stirring vigorously at 1500 r / min for 1 h. The mixture was then sealed and stirred at 900 r / min at 70 °C. After 24 h, the sealing ring was removed, and the mixture was stirred again at 900 r / min in an open-air environment for 24 h. The final product was washed with deionized water and centrifuged at 9000 r / min. This process was repeated 5 times to obtain the product "armored" lignin nanoparticles (AS-OL NPs).

[0143] (3) Preparation of a barrier-resistant, biodegradable, and antibacterial food preservation film with an "armor" lignin content of 3%.

[0144] 2.00 g cellulose acetate, 7.00 mg acetone, and 3.00 mL N,N-dimethylformamide were mixed in a three-necked flask and stirred at a high speed of 500 r / min until completely dissolved. Then, 60.00 mg of the "armored" lignin nanoparticles prepared in step (2) above were added to the flask and stirred until completely dissolved to obtain a spinning solution for electrospinning. The spinning solution was transferred to a 10.00 mL syringe (equipped with a 1.5 mm needle) and extruded at a controlled rate (1.00 mL / min) using a syringe pump while applying a voltage of 20.00 kV to the needle. The nanofibers prepared by electrospinning were collected on a roller receiver covered with aluminum foil and dried at 80 °C for 2 h to obtain a barrier biodegradable antibacterial food preservation film with a "armored" lignin content of 3%.

[0145] Example 2

[0146] Except for changing the lignin in the preparation of the above (2) "armor" lignin nanoparticles to lignin (DL, the product of CuMnO2 nanoenzyme degradation of OL lignin, DL has a higher molecular weight than EL), the preparation was carried out in the same manner as in Example 1.

[0147] The "armored" lignin nanoparticles prepared in this embodiment are denoted as "AS-DL NPs".

[0148] Example 3

[0149] Except for changing the lignin in the preparation of the above (2) "armor" lignin nanoparticles to lignin (EL, the product of CuMnO2 nanoenzyme degrading OL lignin), the preparation was carried out in the same manner as in Example 1.

[0150] The "armored" lignin nanoparticles prepared in this embodiment are denoted as "AS-EL NPs".

[0151] Figure 1b The epoxidized soybean oil acrylate (AESO) shown in Examples 1-3 is illustrated. 1 H NMR spectrum: 1 H NMR (600MHz, CDCl3, TMS, δ): 5.26 (s, 3H, OH), 4.15-4.29 (m, 6H, CHOCH), 2.89-3.11 (m, 9H, C H2=CH), 2.31(t,3H,CHOH), 1.74(m,3H,CHO), 1.25-1.60(m,76H,CH2CH2), 0.88(t,9H,CH3).

[0152] Figure 1c The FTIR characterization of the "armored" lignin nanoparticles in Examples 1-3 is shown: the characteristic peak of the epoxy groups is located at 1743 cm⁻¹. -1 At this point, the -OH peak is located at 3400 cm⁻¹. -1 and 3450cm -1 At this point, the -CH3 and -CH2- peaks are located at 2900 cm⁻¹. -1 and -2800cm -1 At this point, the COC peak is located at 1110 cm⁻¹. -1 Location, 1600cm -1 1512cm -1 and 1454cm -1 The peak at that location can be attributed to the extension of the aromatic ring in the lignin phenylpropane skeleton.

[0153] exist Figure 1c In this text, “AS-OL NPs”, “AS-DL NPs”, and “AS-EL NPs” all refer to “armored” lignin nanoparticles. AS is an abbreviation for epoxidized soybean oil acrylate, OL, DL, and EL represent lignin from different sources (OL represents residual lignin from enzymatically hydrolyzed corn cob manufactured by Shandong Longli Biotechnology Co., Ltd., while DL and EL represent products of CuMnO2 nanoenzyme degradation of OL lignin), and NPs indicates that the final “armored” lignin nanoparticles are nanoscale products.

[0154] Figure 2aThese are scanning electron microscope (SEM) images of the "armored" lignin nanoparticles prepared in Examples 1-3. The SEM images show that the "armored" lignin nanoparticles are uniform in size and well-dispersed.

[0155] Figure 2b These are transmission electron microscope (TEM) images of the "armored" lignin nanoparticles at different magnifications in Example 1. The TEM images show that the "armored" lignin nanoparticles exhibit a bilayer structure: the darker inner portion is composed of lignin, while the lighter outer portion is composed of AESO and PVA.

[0156] Figure 2c The formation process of the "armored" lignin nanoparticles in Example 1 is shown, which is ultimately led to the formation of "armored" lignin nanoparticles through a series of thermally induced electron transfers, proton releases and subsequent free radical coupling.

[0157] Figure 2d The size distribution of the "armored" lignin nanoparticles in Examples 1-3 is shown. The "armored" lignin nanoparticles prepared in Examples 1-3 have a uniform size distribution.

[0158] exist Figure 2d In this text, “AS-OL NPs”, “AS-DL NPs”, and “AS-EL NPs” all refer to “armored” lignin nanoparticles. AS is an abbreviation for epoxidized soybean oil acrylate, OL, DL, and EL represent lignin from different sources (OL represents residual lignin from enzymatically hydrolyzed corn cob manufactured by Shandong Longli Biotechnology Co., Ltd., while DL and EL represent products of CuMnO2 nanoenzyme degradation of OL lignin), and NPs indicates that the final “armored” lignin nanoparticles are nanoscale products.

[0159] Figure 3a These are scanning electron microscope (SEM) images of the "armor" lignin-based products (barrier-resistant biodegradable antibacterial food preservation films with a "armor" lignin content of 3%) from Examples 1-3. The SEM images show that the nanofibers in the "armor" lignin-based products with a "armor" lignin content of 3% are uniformly sized and free of beads.

[0160] Figure 3b Thermogravimetric analysis of the "armored" lignin-based products of Examples 1-3 is shown. As can be seen from the figure, the "armored" lignin-based products of Examples 1-3 exhibit excellent thermal stability.

[0161] Figure 3c The elongation and tensile strength of the "armored" lignin-based articles of Examples 1-3 are shown. As can be seen from the figure, the "armored" lignin-based articles of Examples 1-3 possess excellent mechanical properties.

[0162] Figure 3d The visible and ultraviolet light transmittance of the "armored" lignin-based products of Examples 1-3 is shown. As can be seen from the figure, the "armored" lignin-based products of Examples 1-3 exhibit excellent natural light and ultraviolet light blocking properties.

[0163] Figure 3e The gas separation performance of the "armored" lignin-based products of Examples 1-3 is shown. As can be seen from the figure, the "armored" lignin-based products of Examples 1-3 have excellent gas isolation performance.

[0164] Figure 3f The figure shows the water contact angles of the "armored" lignin-based products of Examples 1-3. As can be seen from the figure, the "armored" lignin-based products of Examples 1-3 exhibit excellent water molecule barrier properties.

[0165] exist Figures 3a-3f In this context, "CA" represents cellulose acetate membrane.

[0166] Figure 4a The antibacterial activity of the "armored" lignin-based products of Examples 1-3 is shown. As can be seen from the figure, the "armored" lignin-based products of Examples 1-3 have excellent antibacterial properties.

[0167] Figure 4b The figure illustrates the practical application of the antioxidant properties of the "armored" lignin-based products of Examples 1-3. As can be seen from the figure, the "armored" lignin-based products of Examples 1-3 exhibit excellent antioxidant properties in practical applications.

[0168] Figure 4c The figure shows the biodegradability of the "armored" lignin-based products of Examples 1-3. As can be seen from the figure, the "armored" lignin-based products of Examples 1-3 exhibit excellent biodegradability.

[0169] Two weeks later, the degradation rate of the CA membrane was 15.7%, the degradation rate of the "armored" lignin-based product (AS-OLNPs / CA) prepared in Example 1 was 19.6%, the degradation rate of the "armored" lignin-based product (AS-DL NPs / CA) prepared in Example 2 was 17.9%, and the degradation rate of the "armored" lignin-based product (AS-EL NPs / CA) prepared in Example 3 was 19.8%.

[0170] exist Figures 4a-4c In this text, "Blank" indicates the control group, with fresh apple pieces used as a control. "CA" represents cellulose acetate membrane.

[0171] <Evaluation Experiment>

[0172] (1) Epoxidized soybean oil acrylate (AESO) 1 H NMR spectroscopy determination:

[0173] 5 mg of sample was dissolved in 0.5 mL of CDCl3-d. The NMR tube containing the CDCl3-d solution was placed in a Luke AVAVCEIII HD 700 MHz spectrometer for measurement at 25 °C. Figure 1b )

[0174] (2) Measurement of the infrared spectrum of "armored" lignin nanoparticles:

[0175] KBr and the sample ("armored" lignin nanoparticles) were mixed in an appropriate ratio to prepare a homogeneous mixture, which was then pressed into a sheet under high pressure. The sample sheet was carefully removed, placed on a magnetic sample holder, and then placed in the sample chamber of an intelligent Fourier transform infrared spectrometer. Measurements were performed under the selected instrument program. Typically, the blank background of KBr was measured first, and then the sample was placed in the optical path to measure the infrared spectrum of the sample (400-4000 cm⁻¹). -1 ). ( Figure 1c )

[0176] (3) Sample morphology analysis:

[0177] Scanning electron microscope (SEM, Jeol JSM-7800F, Japan) was used to detect the morphology of the samples.

[0178] Take a sample of appropriate size, attach it to the sample stage, and after gold sputtering, place it in the detection chamber and evacuate it for observation. The accelerating voltage is 5-15kV. Figure 2a , Figure 3a )

[0179] (4) Detailed structural morphological analysis of the sample's internal structure:

[0180] Transmission electron microscopy (TEM, JEM-2100 (UHR)) was used to detect the fine internal structure of the sample.

[0181] Take appropriate amounts of powder and ethanol and add them separately to small beakers. Sonicate for 10–30 minutes. After 3–5 minutes, use a glass capillary tube to draw up the homogeneous mixture of powder and ethanol, then drop 2–3 drops of this mixture onto a microgrid. Wait at least 15 minutes to allow the ethanol to evaporate as much as possible. Place the sample in a detection chamber and evacuate it for observation. Use an accelerating voltage of 5–15 kV. Figure 2b )

[0182] (5) Particle size determination:

[0183] Particle size was measured using dynamic light scattering technology with a nanoparticle size and Zeta potential analyzer (Opptronix-929SZ). Figure 2d )

[0184] (6) Thermal stability analysis:

[0185] The thermal stability of the samples was tested using a thermogravimetric analyzer (TGA, TAQ50, USA). 5–10 mg of sample was weighed and spread evenly in a platinum test pan. The pan was heated from room temperature to 700°C at a rate of 10°C / min under a nitrogen atmosphere (flow rate 40 mL / min). Figure 3b )

[0186] (7) Mechanical property testing:

[0187] The tensile strength of the nanofibers was tested using a universal testing machine (Shimadze AGS-X, Japan). Nanofiber mats were cut into 1×5cm specimen strips. To prevent breakage at the clamping points during testing, 2×2cm pieces of cardboard were glued to both ends of the specimen strips with quick-drying adhesive. The specimens were clamped onto the cardboard for testing, with an effective test length of 3cm. A 50N sensor was applied, and the testing rate was 2mm / min. Ten samples were tested in each group, and the average value was calculated. Figure 3c )

[0188] (8) UV resistance test:

[0189] All samples were wrapped in paper tape for UV transmittance measurement (at least three samples were prepared for each UV transmittance measurement). The samples were placed in darkness. The UV transmittance of the samples was measured using a Cary 100 spectrophotometer (Agilent Technologies, USA). 3-5 points were scanned for each sample. For each scan, transmittance (T) measurements were collected in the wavelength range from UVB (290-320 nm) to UVA (320-400 nm). Figure 3d )

[0190] (9) O2 gas permeation test:

[0191] A differential pressure gas transfer instrument (GTR TEC-GTR-11MH, Kyoto, Japan); test area: 0.785 cm² 2 Measurements were performed. The instrument's test temperature was 34℃, and the test pressure was maintained at 49 kPa (0.1 MPa). The carrier gas was H2 at a pressure of 0.5 MPa. The sample was placed at the inlet, and timing began when gas passage was detected. The gas permeation of the membrane was measured after 2 hours. Figure 3e )

[0192] (10) Contact angle test:

[0193] The solid sample is placed on the sample stage of the fully automated contact angle tester (Dynetech-SCD-350), and the test liquid is dropped onto the solid sample. The image of the droplet is recorded using a camera, and the contact angle of the droplet on the solid surface can be analyzed by fitting the droplet's profile in the analysis software. Figure 3f )

[0194] (11) Antibacterial performance test: Figure 4a )

[0195] Bacterial culture: The antibacterial activity of the tested fiber membranes was determined by colony forming unit (CFU) counting. Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were cultured in Luria-Bertani (LB) medium (10 g / L tryptone, 5.0 g / L yeast extract and 10 g / L sodium chloride, pH 7.0).

[0196] Preparation of LB agar plates: Add 1.5% (w / v) agar to LB medium. Inoculate one colony into LB medium and incubate at 37°C for 12–16 h.

[0197] Antibacterial performance test: The culture (1:50, v / v) and the fiber membrane to be tested (4×4cm) were mixed. 2 Add to 5 mL of LB medium. After incubating at 37°C for 2 h, dilute the culture with fresh sterile medium, then drop 200 μL of the suspension onto LB agar plates and incubate overnight at 37°C. Count CFU the next day. Repeat each experiment three times, and calculate the total number of bacterial colonies in the original sample based on the dilution factor.

[0198] (12) Preservation performance test:

[0199] Cut the selected fresh apple into 1cm pieces. 3 Small cubes were prepared and placed in plastic petri dishes. Then, the prepared fibrous membrane was placed over the surface of the plastic petri dishes. Finally, the dishes were stored at room temperature for 3 days and photographed periodically. Fresh apple slices were used as a control. Figure 4b )

[0200] (13) Natural degradation performance test:

[0201] The prepared fiber membrane was cut into pieces of approximately 3×3cm. 2 The samples were buried approximately 4 cm deep in natural soil. After 1 and 2 weeks, the degradation samples and fragments were removed, and residual soil was gently washed away with distilled water. The samples were then dried at 37°C until a constant weight was achieved. Finally, the weight of the dried samples was weighed again, and the weight loss of the degradation film in the soil was calculated. The degradation rate was calculated using the following formula. Figure 4c )

[0202]

[0203] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0204] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing an article based on "armor" lignin, characterized in that, The preparation method includes: Process A: A mixture of lignin, acrylate functional group derivatives of natural oils, and polyvinyl alcohol is used to obtain "armored" lignin nanoparticles; and Step B: Prepare "armored" lignin-based products by electrospinning the spinning solution containing the "armored" lignin nanoparticles. The mass ratio of the lignin to the acrylate functional group derivative of the natural oil is 1:1 to 1:

2. The product based on "armor" lignin contains 1-3% by mass of "armor" lignin nanoparticles; The "armored" lignin nanoparticles include a core and a shell covering at least a portion of the outer surface of the core. The core contains lignin. The shell contains acrylate functional group derivatives of natural oils and polyvinyl alcohol.

2. The preparation method according to claim 1, characterized in that, The acrylate functional group derivatives of the natural oils include acrylate functional group derivatives of soybean oil.

3. The preparation method according to claim 2, characterized in that, The acrylate functional group derivatives of soybean oil include epoxidized soybean oil acrylate.

4. The preparation method according to claim 2, characterized in that, The process A includes: Step A1: A mixture comprising an epoxy compound and acrylic acid is mixed with at least one selected from the group consisting of polymerization inhibitors and catalysts to obtain an acrylate functional group derivative of natural oil. Step A2: Mix lignin, acrylate functional group derivatives of the natural oil obtained in Step A1, and polyvinyl alcohol to obtain "armored" lignin nanoparticles.

5. The preparation method according to claim 4, characterized in that, The process A1 satisfies at least one of the following: (a) The ratio of the number of epoxy groups in the epoxy compound to the number of carboxyl groups in the acrylic acid is 1:1 to 1.2:1; (b) The epoxy compound comprises epoxidized soybean oil; (c) The polymerization inhibitor is 4-methoxyphenol; (d) The catalyst is anthraquinone; (e) The mass ratio of the epoxy compound to the acrylic acid is 14:1 to 15:1; (f) The mass ratio of the polymerization inhibitor to the epoxy compound is 1:1000 to 1:900; (g) The mass ratio of the catalyst to the epoxide is 1:77 to 1:78; (h) Stop the reaction when the acid value of the reactants is below 8 mg / g.

6. The preparation method according to any one of claims 1 to 5, characterized in that, Process B includes the following processes: Step B1: Mix the "armor" lignin nanoparticles, cellulose acetate, and organic solvent to obtain a spinning solution; Step B2: Prepare "armored" lignin-based products by electrospinning the spinning solution.

7. The preparation method according to claim 6, characterized in that, The process B1 satisfies at least one of the following: (i) The organic solvent comprises acetone and N,N-dimethylformamide; (j) Cellulose acetate accounts for 40-45% of the total mass of the spinning solution; (k) The mass of acetone accounts for 0.1 to 0.2% of the total mass of the spinning solution; (l) N,N-dimethylformamide accounts for 57-60% of the total mass of the spinning solution; (m) "Armor" lignin nanoparticles account for 1-2% of the total mass of the spinning solution.

8. The preparation method according to claim 6, characterized in that, In step B2, the conditions for electrospinning are as follows: the syringe volume is 10.00 mL, the syringe is equipped with a 1.5 mm needle, the controllable extrusion rate is 1.00 mL / min, and the voltage applied to the needle is 20.00 kV.

9. An article based on "armor" lignin, characterized in that, The product based on "armor" lignin is obtained by the preparation method according to any one of claims 1 to 8.

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